JavaScript & TypeScript Errors

JavaScript and TypeScript errors hit at three layers: the type system (TypeScript catches at compile time), the runtime (Node.js, browser), and the toolchain (npm, Vite, webpack, tsc). The error message often points at the wrong layer — a TypeScript error can be a tsconfig issue, a Node crash can be a missing peer dependency.

This hub covers errors that are not framework-specific. For framework errors, see React & Frontend.

Recommended starting points:

• Module not found / Cannot resolve — the most common module resolution failure.
• TypeScript: Cannot find module — type-only resolution problems.
• Unhandled promise rejection — silent killers in async code.

TypeScript (217)

• Fix: AWS Amplify Not Working — Gen 2 Backend, defineData, Auth, Storage, and Sandbox Deployments

  How to fix AWS Amplify Gen 2 errors — backend.ts file structure, defineData schema authorization, defineAuth flow, defineStorage bucket access, sandbox vs branch deploy, generated outputs, and Cognito triggers.

• Fix: Astro Content Collections Not Working — Content Layer, Loaders, Schema, and References

  How to fix Astro content collections errors — content/config.ts moved to content.config.ts, glob loader patterns, schema validation, references between collections, live reload on add/remove, and remote loaders.

• Fix: Bun Bundler Not Working — Targets, Format, Externals, Macros, and Code Splitting

  How to fix bun build errors — target (browser/bun/node) mismatch, format esm/cjs/iife, externals not respected, Bun macros at compile time, splitting and chunks, plugin API, and Bun.build vs CLI.

• Fix: Bun Shell Not Working — $ Template Quoting, Pipes, Exit Codes, and Cross-Platform Scripts

  How to fix Bun Shell errors — $ template auto-escape vs raw strings, piping with pipe() vs |, throws on non-zero exit, cwd/env scoping, glob expansion differences, and Windows path handling.

• Fix: ESLint Flat Config Not Working — eslint.config.js, ignores, Plugins, and Migration

  How to fix ESLint flat config errors — eslint.config.js not found, .eslintrc.json ignored after upgrade, ignores replacing .eslintignore, plugin object form, typescript-eslint integration, monorepo configs, and ESLINT_USE_FLAT_CONFIG.

• Fix: Mongoose Not Working — Connection Options Removed, strictQuery, populate, and Lean Queries

  How to fix Mongoose errors — useNewUrlParser removed, strictQuery default flip, populate returning null, lean() losing methods, discriminator setup, transaction sessions, and TypeScript Document types.

• Fix: Node.js Test Runner Not Working — node --test, TypeScript, Mocks, Coverage, and Watch Mode

  How to fix Node.js built-in test runner errors — node --test not finding files, ESM vs CJS imports, TypeScript with --experimental-strip-types, mock.method isolation, coverage reporting, and watch mode setup.

• Fix: Nx Not Working — project.json Targets, Affected Commands, Caching, and Generators

  How to fix Nx errors — nx.json plugin config, project.json target inputs/outputs, nx affected base branch, cache misses, generator schema, custom executors, and nx migrate failures.

• Fix: Oxlint Not Working — .oxlintrc.json Config, Rule Mapping, TypeScript, and ESLint Coexistence

  How to fix Oxlint errors — .oxlintrc.json not loaded, rules not matching ESLint output, TypeScript files not linted, plugin-react/typescript wiring, IDE extension setup, and running alongside ESLint.

• Fix: Pulumi Not Working — Output<T>, Stack References, Secrets, State Backend, and Preview vs Up

  How to fix Pulumi errors — Output<T> can't be unwrapped synchronously, stack reference not found, secret leaks in stack outputs, state backend lock, ResourceOptions parent missing, and refresh drift.

• Fix: tsx Not Working — ESM Imports, Watch Mode, Path Aliases, and node --import tsx

  How to fix tsx (TypeScript executor) errors — Cannot find module after upgrade, ESM .js extension required, tsconfig paths not respected, watch mode not restarting, --import vs --loader, VS Code debugger setup.

• Fix: Valibot Not Working — v.pipe Syntax, Error Messages, Async Validation, and Zod Migration

  How to fix Valibot errors — v.pipe vs chained methods, parse vs safeParse, async pipelines with v.parseAsync, custom error messages with v.message, optional/nullable variants, Zod migration patterns, and form library integration.

• Fix: Bun Test Not Working — Module Mocking, DOM Setup, Coverage, and Watch Mode

  How to fix Bun test runner issues — mock.module not isolating, happy-dom setup for DOM tests, --coverage missing files, timer mocks, snapshot updates, TypeScript path aliases, and preload files.

• Fix: Hono RPC Not Working — Client Type Inference, AppType Export, Validators, and Path Params

  How to fix Hono RPC client errors — hc<AppType> showing any, validator types not flowing, app.route chaining loses types, monorepo type import, path param typing, JSON body validation, and streaming.

• Fix: Next.js 'params should be awaited before using its properties'

  How to fix Next.js 15 async params and searchParams errors — await in Server Components, React.use in Client Components, generateMetadata, generateStaticParams, and the codemod migration path.

• Fix: React Router 7 Not Working — Framework Mode, Loaders, Type Safety, and Remix Migration

  How to fix React Router v7 errors — framework mode vs library mode setup, loader/action data type narrowing, route module exports missing, single-fetch revalidation, hydration mismatch, and Remix v2 migration paths.

• Fix: SWR Not Working — Key Changes, Mutate Not Updating, Conditional Fetching, and SSR Hydration

  How to fix SWR errors — useSWR not refetching on key change, mutate not invalidating, conditional null key, fallbackData vs fallback, SSR hydration mismatch, infinite scroll pagination, and TypeScript typing.

• Fix: TanStack Form Not Working — Field Types, Validators, Async Validation, and Subscription Re-renders

  How to fix TanStack Form errors — field name not typed, zod/valibot validators not running, async onChange race conditions, listener not firing, array field state, and SSR with Server Actions.

• Fix: AWS CDK Not Working — Bootstrap Error, ROLLBACK_COMPLETE, and Deploy Failures

  How to fix AWS CDK errors — cdk bootstrap required, stack in ROLLBACK_COMPLETE, asset bundling failed, CLI/library version mismatch, VPC lookup failing, and cross-stack export conflicts.

• Fix: Deno PermissionDenied — Missing --allow-read, --allow-net, and Other Flags

  How to fix Deno PermissionDenied (NotCapable in Deno 2) errors — the right permission flags, path-scoped permissions, deno.json permission sets, and the Deno.permissions API.

• Fix: Fastify Not Working — 404, Plugin Encapsulation, and Schema Validation Errors

  How to fix Fastify issues — route 404 from plugin encapsulation, reply already sent, FST_ERR_VALIDATION, request.body undefined, @fastify/cors, hooks not running, and TypeScript type inference.

• Fix: Temporal Not Working — Workflows Not Starting, Activities Failing, or Worker Not Connecting

  How to fix Temporal issues — worker setup, workflow and activity errors, schedule configuration, versioning, and self-hosted Temporal Server deployment.

• Fix: UploadThing Not Working — File Upload Failing, CORS Errors, or Route Not Found

  How to fix UploadThing issues — file router configuration, Next.js App Router and Pages Router setup, CORS, file type restrictions, progress callbacks, and deployment.

• Fix: Analog Not Working — Routes Not Loading, API Endpoints Failing, or Vite Build Errors

  How to fix Analog (Angular meta-framework) issues — file-based routing, API routes with Nitro, content collections, server-side rendering, markdown pages, and deployment.

• Fix: Angular SSR Not Working — Hydration Failing, Window Not Defined, or Build Errors

  How to fix Angular Server-Side Rendering issues — @angular/ssr setup, hydration, platform detection, transfer state, route-level rendering, and deployment configuration.

• Fix: Astro DB Not Working — Tables Not Found, Queries Failing, or Seed Data Missing

  How to fix Astro DB issues — schema definition, seed data, queries with drizzle, local development, remote database sync, and Astro Studio integration.

• Fix: Astro Actions Not Working — Form Submission Failing, Validation Errors Missing, or Return Type Wrong

  How to fix Astro Actions issues — action definition, Zod validation, form handling, progressive enhancement, error handling, file uploads, and calling actions from client scripts.

• Fix: Expo Router Not Working — Routes Not Matching, Layout Nesting Wrong, or Deep Links Failing

  How to fix Expo Router issues — file-based routing, layout routes, dynamic segments, tabs and stack navigation, modal routes, authentication flows, and deep linking configuration.

• Fix: React Native Paper Not Working — Theme Not Applying, Icons Missing, or Components Unstyled

  How to fix React Native Paper issues — PaperProvider setup, Material Design 3 theming, custom color schemes, icon configuration, dark mode, and Expo integration.

• Fix: React Navigation Not Working — Screens Not Rendering, TypeScript Errors, or Gestures Broken

  How to fix React Navigation issues — stack and tab navigator setup, TypeScript typing, deep linking, screen options, nested navigators, authentication flow, and performance optimization.

• Fix: SolidStart Not Working — Routes Not Rendering, Server Functions Failing, or Hydration Errors

  How to fix SolidStart issues — file-based routing, server functions, createAsync data loading, middleware, sessions, and deployment configuration.

• Fix: TanStack Start Not Working — Server Functions Failing, Routes Not Loading, or SSR Errors

  How to fix TanStack Start issues — project setup, file-based routing, server functions with createServerFn, data loading, middleware, SSR hydration, and deployment configuration.

• Fix: Vinxi Not Working — Dev Server Not Starting, Routes Not Matching, or Build Failing

  How to fix Vinxi server framework issues — app configuration, routers, server functions, middleware, static assets, and deployment to different platforms.

• Fix: Waku Not Working — Server Components Not Rendering, Client Components Not Interactive, or Build Errors

  How to fix Waku React framework issues — RSC setup, server and client component patterns, data fetching, routing, layout system, and deployment configuration.

• Fix: Wasp Not Working — Build Failing, Auth Not Working, or Operations Returning Empty

  How to fix Wasp full-stack framework issues — main.wasp configuration, queries and actions, authentication setup, Prisma integration, job scheduling, and deployment.

• Fix: Better Auth Not Working — Login Failing, Session Null, or OAuth Callback Error

  How to fix Better Auth issues — server and client setup, email/password and OAuth providers, session management, middleware protection, database adapters, and plugin configuration.

• Fix: BullMQ Not Working — Jobs Not Processing, Workers Not Starting, or Redis Connection Failing

  How to fix BullMQ issues — queue and worker setup, Redis connection, job scheduling, retry strategies, concurrency, rate limiting, event listeners, and dashboard monitoring.

• Fix: Changesets Not Working — Version Not Bumping, Changelog Empty, or GitHub Action Failing

  How to fix @changesets/cli issues — changeset creation, version bumping, changelog generation, monorepo support, npm publishing, and GitHub Actions automation.

• Fix: Clack Not Working — Prompts Not Displaying, Spinners Stuck, or Cancel Not Handled

  How to fix @clack/prompts issues — interactive CLI prompts, spinners, multi-select, confirm dialogs, grouped tasks, cancellation handling, and building CLI tools with beautiful output.

• Fix: Clerk Not Working — Auth Not Loading, Middleware Blocking, or User Data Missing

  How to fix Clerk authentication issues — ClerkProvider setup, middleware configuration, useUser and useAuth hooks, server-side auth, webhook handling, and organization features.

• Fix: cmdk Not Working — Command Palette Not Opening, Items Not Filtering, or Keyboard Navigation Broken

  How to fix cmdk command palette issues — Dialog setup, custom filtering, groups and separators, keyboard shortcuts, async search, nested pages, and integration with shadcn/ui and Tailwind.

• Fix: CodeMirror Not Working — Editor Not Rendering, Extensions Not Loading, or React State Out of Sync

  How to fix CodeMirror 6 issues — basic setup, language and theme extensions, React integration, vim mode, collaborative editing, custom keybindings, and read-only mode.

• Fix: Conform Not Working — Form Validation Not Triggering, Server Errors Missing, or Zod Schema Rejected

  How to fix Conform form validation issues — useForm setup with Zod, server action integration, nested and array fields, file uploads, progressive enhancement, and Remix and Next.js usage.

• Fix: Contentlayer Not Working — Content Not Generated, Types Missing, or Build Errors

  How to fix Contentlayer and Contentlayer2 issues — content source configuration, document type definitions, MDX processing, computed fields, Next.js integration, and migration to alternatives.

• Fix: ElectricSQL Not Working — Sync Not Starting, Shapes Empty, or Postgres Connection Failing

  How to fix ElectricSQL issues — Postgres setup with logical replication, shape definitions, real-time sync to the client, React hooks, write-path through the server, and deployment configuration.

• Fix: gql.tada Not Working — Types Not Inferred, Schema Not Found, or IDE Not Showing Completions

  How to fix gql.tada issues — schema introspection, type-safe GraphQL queries, fragment masking, urql and Apollo Client integration, IDE setup, and CI type checking.

• Fix: GraphQL Yoga Not Working — Schema Errors, Resolvers Not Executing, or Subscriptions Failing

  How to fix GraphQL Yoga issues — schema definition, resolver patterns, context and authentication, file uploads, subscriptions with SSE, error handling, and Next.js integration.

• Fix: GSAP Not Working — Animations Not Playing, ScrollTrigger Not Firing, or React Cleanup Issues

  How to fix GSAP animation issues — timeline and tween basics, ScrollTrigger setup, React useGSAP hook, cleanup and context, SplitText, stagger animations, and Next.js integration.

• Fix: i18next Not Working — Translations Missing, Language Not Switching, or Namespace Errors

  How to fix i18next issues — react-i18next setup, translation file loading, namespace configuration, language detection, interpolation, pluralization, and Next.js integration.

• Fix: ky Not Working — Requests Failing, Hooks Not Firing, or Retry Not Working

  How to fix ky HTTP client issues — instance creation, hooks (beforeRequest, afterResponse), retry configuration, timeout handling, JSON parsing, error handling, and migration from fetch or axios.

• Fix: LangChain.js Not Working — Chain Not Executing, Retriever Returning Empty, or Memory Lost Between Calls

  How to fix LangChain.js issues — model setup, prompt templates, RAG with vector stores, conversational memory, structured output, tool agents, and streaming with LangChain Expression Language.

• Fix: Lingui Not Working — Messages Not Extracted, Translations Missing, or Macro Errors

  How to fix Lingui.js i18n issues — setup with React, message extraction, macro compilation, ICU format, lazy loading catalogs, and Next.js integration.

• Fix: Mantine Not Working — Styles Not Loading, Theme Not Applying, or Components Broken After Upgrade

  How to fix Mantine UI issues — MantineProvider setup, PostCSS configuration, theme customization, dark mode, form validation with useForm, and Next.js App Router integration.

• Fix: Mapbox GL JS Not Working — Map Not Rendering, Markers Missing, or Access Token Invalid

  How to fix Mapbox GL JS issues — access token setup, React integration with react-map-gl, markers and popups, custom layers, geocoding, directions, and Next.js configuration.

• Fix: Monaco Editor Not Working — Editor Not Loading, TypeScript Errors, or Web Workers Failing

  How to fix Monaco Editor issues — React integration with @monaco-editor/react, worker setup, TypeScript IntelliSense, custom themes, multi-file editing, and Next.js configuration.

• Fix: next-safe-action Not Working — Action Not Executing, Validation Errors Missing, or Type Errors

  How to fix next-safe-action issues — action client setup, Zod schema validation, useAction and useOptimisticAction hooks, middleware, error handling, and authorization patterns.

• Fix: nuqs Not Working — URL State Not Syncing, Type Errors, or Server Component Issues

  How to fix nuqs URL search params state management — useQueryState and useQueryStates setup, parsers, server-side access, shallow routing, history mode, and Next.js App Router integration.

• Fix: Orval Not Working — Code Generation Failing, Types Not Matching API, or Hooks Not Updating

  How to fix Orval API client generation issues — OpenAPI spec configuration, custom output targets, React Query and Axios integration, mock generation, type overrides, and CI/CD automation.

• Fix: pdf-lib Not Working — PDF Not Generating, Fonts Not Embedding, or Pages Blank

  How to fix pdf-lib issues — creating PDFs from scratch, modifying existing PDFs, embedding fonts and images, form filling, merging documents, and browser and Node.js usage.

• Fix: Paraglide Not Working — Messages Not Loading, Compiler Errors, or Framework Integration Issues

  How to fix Paraglide.js i18n issues — message compilation, type-safe translations, SvelteKit and Next.js integration, language switching, and message extraction from existing code.

• Fix: PostHog Not Working — Events Not Tracking, Feature Flags Stale, or Session Replay Blank

  How to fix PostHog analytics issues — JavaScript and Next.js setup, event capture, feature flags, A/B testing, session replay, user identification, and server-side tracking.

• Fix: Pothos Not Working — Types Not Resolving, Plugin Errors, or Prisma Integration Failing

  How to fix Pothos GraphQL schema builder issues — type-safe schema definition, object and input types, Prisma plugin, relay connections, auth scope plugin, and schema printing.

• Fix: PowerSync Not Working — Offline Sync Failing, Queries Returning Stale Data, or Backend Connection Errors

  How to fix PowerSync issues — SQLite local database, sync rules configuration, backend connector setup, watched queries, offline-first patterns, and React and React Native integration.

• Fix: publint Not Working — Package Exports Invalid, Types Not Found, or Dual Package Errors

  How to fix publint package validation issues — exports field configuration, dual ESM/CJS packaging, type resolution, main/module/types fields, files array, and common packaging mistakes.

• Fix: Pusher Not Working — Events Not Received, Channel Auth Failing, or Connection Dropping

  How to fix Pusher real-time issues — client and server setup, channel types, presence channels, authentication endpoints, event binding, connection management, and React integration.

• Fix: React Aria Not Working — Components Not Rendering, ARIA Attributes Missing, or Styling Conflicts

  How to fix React Aria and React Aria Components issues — hooks vs components API, styling with Tailwind CSS, custom components, collections pattern, forms, and accessibility compliance.

• Fix: React PDF Not Working — PDF Not Rendering, Worker Error, or Pages Blank

  How to fix react-pdf and @react-pdf/renderer issues — PDF viewer setup, worker configuration, page rendering, text selection, annotations, and generating PDFs in React.

• Fix: React Three Fiber Not Working — Canvas Blank, Models Not Loading, or Performance Dropping

  How to fix React Three Fiber (R3F) issues — Canvas setup, loading 3D models with useGLTF, lighting, camera controls, animations with useFrame, post-processing, and Next.js integration.

• Fix: Scalar Not Working — API Docs Not Rendering, Try-It Not Sending Requests, or Theme Broken

  How to fix Scalar API documentation issues — OpenAPI spec loading, interactive Try-It panel, authentication configuration, custom themes, CDN and React integration, and self-hosting.

• Fix: Sentry Not Working — Errors Not Captured, Source Maps Missing, or Performance Traces Empty

  How to fix Sentry issues — SDK initialization, source map uploads, error boundaries, performance monitoring, Next.js integration, release tracking, and alert configuration.

• Fix: Sharp Not Working — Installation Failing, Image Not Processing, or Build Errors on Deploy

  How to fix Sharp image processing issues — native binary installation, resize and convert operations, Next.js image optimization, Docker setup, serverless deployment, and common platform errors.

• Fix: Shiki Not Working — No Syntax Highlighting, Wrong Theme, or Build Errors

  How to fix Shiki syntax highlighter issues — basic setup, theme configuration, custom languages, transformer plugins, Next.js and Astro integration, and bundle size optimization.

• Fix: Sonner Not Working — Toasts Not Showing, Styling Broken, or Server Component Errors

  How to fix Sonner toast notification issues — Toaster setup, toast types, custom styling, promise toasts, action buttons, positioning, dark mode, and Next.js App Router integration.

• Fix: Stripe Integration Not Working — Checkout Failing, Webhooks Not Firing, or Subscriptions Not Updating

  How to fix Stripe issues in Node.js and Next.js — Checkout Sessions, webhook signature verification, subscription lifecycle, customer portal, price management, and idempotent API calls.

• Fix: Supertest Not Working — Requests Not Sending, Server Not Closing, or Assertions Failing

  How to fix Supertest HTTP testing issues — Express and Fastify setup, async test patterns, authentication headers, file uploads, JSON body assertions, and Vitest/Jest integration.

• Fix: Trigger.dev Not Working — Tasks Not Running, Runs Failing, or Dev Server Not Connecting

  How to fix Trigger.dev issues — task definition and triggering, dev server setup, scheduled tasks with cron, concurrency and queues, retries, idempotency, and deployment to Trigger.dev Cloud.

• Fix: tsup Not Working — Build Failing, Types Not Generated, or ESM/CJS Output Wrong

  How to fix tsup bundler issues — entry points, dual ESM/CJS output, TypeScript declaration files, external dependencies, tree shaking, and package.json exports configuration.

• Fix: ts-rest Not Working — Contract Types Not Matching, Client Requests Failing, or Server Validation Errors

  How to fix ts-rest issues — contract definition, type-safe client and server setup, Zod validation, Next.js App Router integration, error handling, and OpenAPI generation.

• Fix: unbuild Not Working — Build Output Empty, Stub Mode Failing, or Rollup Errors

  How to fix unbuild issues — build configuration, stub mode for development, ESM and CJS output, TypeScript declarations, external dependencies, and monorepo workspace builds.

• Fix: Vercel AI SDK Not Working — Streaming Not Rendering, useChat Stuck Loading, or Provider Errors

  How to fix Vercel AI SDK issues — useChat and useCompletion hooks, streaming responses with streamText, provider configuration for OpenAI and Anthropic, tool calling, and Next.js integration.

• Fix: Auth.js (NextAuth) Not Working — Session Null, OAuth Callback Error, or CSRF Token Mismatch

  How to fix Auth.js and NextAuth.js issues — OAuth provider setup, session handling in App Router and Pages Router, JWT vs database sessions, middleware protection, and credential provider configuration.

• Fix: Capacitor Not Working — Build Failing, Plugins Not Loading, or Native Features Not Available

  How to fix Capacitor issues — project setup with Ionic or standalone, native plugin access, iOS and Android build errors, live reload, deep links, push notifications, and migration from Cordova.

• Fix: Cypress Not Working — Tests Timing Out, Elements Not Found, or cy.intercept Not Matching

  How to fix Cypress issues — element selection strategies, async command chaining, cy.intercept for network stubbing, component testing, authentication handling, and flaky test debugging.

• Fix: Effect (effect-ts) Not Working — Effect Not Running, Services Missing, or Type Errors

  How to fix Effect issues — running effects with Effect.runPromise, Layer and service dependency injection, error channel types, Fiber concurrency, Schema validation, and common TypeScript errors.

• Fix: Electron Not Working — Window Not Showing, IPC Not Communicating, or Build Failing

  How to fix Electron issues — main and renderer process setup, IPC communication with contextBridge, preload scripts, auto-update, native module rebuilding, and packaging with electron-builder.

• Fix: Inngest Not Working — Functions Not Triggering, Steps Failing, or Events Not Received

  How to fix Inngest issues — function and event setup, step orchestration, retries and error handling, cron scheduling, concurrency control, fan-out patterns, and local development with the Dev Server.

• Fix: jose JWT Not Working — Token Verification Failing, Invalid Signature, or Key Import Errors

  How to fix jose JWT issues — signing and verifying tokens with HS256 and RS256, JWK and JWKS key handling, token expiration, claims validation, and edge runtime compatibility.

• Fix: Liveblocks Not Working — Room Not Connecting, Presence Not Syncing, or Storage Mutations Lost

  How to fix Liveblocks issues — room setup, real-time presence with useOthers, conflict-free storage with useMutation, Yjs integration, authentication, and React suspense patterns.

• Fix: Million.js Not Working — Compiler Errors, Components Not Optimized, or React Compatibility Issues

  How to fix Million.js issues — compiler setup with Vite and Next.js, block() optimization rules, component compatibility constraints, automatic mode, and debugging performance gains.

• Fix: Neon Database Not Working — Connection Timeout, Branching Errors, or Serverless Driver Issues

  How to fix Neon Postgres issues — connection string setup, serverless HTTP driver vs TCP, database branching, connection pooling, Drizzle and Prisma integration, and cold start optimization.

• Fix: Nitro Not Working — Server Routes Not Found, Middleware Not Running, or Deploy Failing

  How to fix Nitro server engine issues — route handlers, middleware, storage with unstorage, caching, WebSocket support, deployment presets for Cloudflare Workers, Vercel, and Node.js.

• Fix: Panda CSS Not Working — Styles Not Applying, Tokens Not Resolving, or Build Errors

  How to fix Panda CSS issues — PostCSS setup, panda.config.ts token system, recipe and pattern definitions, conditional styles, responsive design, and integration with Next.js and Vite.

• Fix: Payload CMS Not Working — Collections Not Loading, Auth Failing, or Admin Panel Blank

  How to fix Payload CMS issues — collection and global config, access control, hooks, custom fields, REST and GraphQL APIs, Next.js integration, and database adapter setup.

• Fix: Qwik Not Working — Components Not Rendering, useSignal Not Reactive, or Serialization Errors

  How to fix Qwik issues — component$ boundaries, useSignal and useStore reactivity, serialization with dollar signs, useTask$ and useVisibleTask$, Qwik City routing, and integration with React components.

• Fix: Radix UI Not Working — Popover Not Opening, Dialog Closing Immediately, or Styling Breaking

  How to fix Radix UI issues — Popover and Dialog setup, controlled vs uncontrolled state, portal rendering, animation with CSS or Framer Motion, accessibility traps, and Tailwind CSS integration.

• Fix: React Email and Resend Not Working — Emails Not Sending, Templates Not Rendering, or Styling Broken

  How to fix React Email and Resend issues — email template components, inline styles, Resend API integration, preview server, attachments, and email client compatibility.

• Fix: Rspack Not Working — Build Failing, Loaders Not Applying, or Dev Server Not Starting

  How to fix Rspack issues — configuration migration from webpack, loader compatibility, CSS extraction, module federation, React Fast Refresh, and build performance tuning.

• Fix: SST Not Working — Deploy Failing, Bindings Not Linking, or Lambda Functions Timing Out

  How to fix SST (Serverless Stack) issues — resource configuration with sst.config.ts, linking resources to functions, local dev with sst dev, database and storage setup, and deployment troubleshooting.

• Fix: Svelte 5 Runes Not Working — $state Not Reactive, $derived Not Updating, or $effect Running Twice

  How to fix Svelte 5 Runes issues — $state and $state.raw reactivity, $derived computations, $effect lifecycle, $props and $bindable, migration from Svelte 4 stores, and component patterns.

• Fix: TanStack Router Not Working — Routes Not Matching, Loader Not Running, or Type Errors

  How to fix TanStack Router issues — file-based routing setup, route tree generation, loader and search params, authenticated routes, type-safe navigation, and code splitting.

• Fix: Turso Not Working — Connection Refused, Queries Returning Empty, or Embedded Replicas Not Syncing

  How to fix Turso database issues — libsql client setup, connection URLs and auth tokens, embedded replicas for local-first apps, schema migrations, Drizzle ORM integration, and edge deployment.

• Fix: UnoCSS Not Working — Classes Not Generating, Presets Missing, or Attributify Mode Broken

  How to fix UnoCSS issues — Vite plugin setup, preset configuration, attributify mode, icons preset, shortcuts, custom rules, and integration with Next.js, Nuxt, and Astro.

• Fix: Upstash Not Working — Redis Commands Failing, Rate Limiter Not Blocking, or QStash Messages Lost

  How to fix Upstash issues — Redis REST client setup, rate limiting with @upstash/ratelimit, QStash message queues, Kafka topics, Vector search, and edge runtime integration.

• Fix: Vanilla Extract Not Working — Styles Not Applied, TypeScript Errors, or Build Failing

  How to fix Vanilla Extract issues — .css.ts file setup, style and recipe APIs, sprinkles for utility classes, theme tokens, dynamic styles, and integration with Next.js, Vite, and Remix.

• Fix: Wrangler Not Working — Deploy Failing, Bindings Not Found, or D1 Queries Returning Empty

  How to fix Wrangler and Cloudflare Workers issues — wrangler.toml configuration, KV and D1 bindings, R2 storage, environment variables, local dev with Miniflare, and deployment troubleshooting.

• Fix: Biome Not Working — Rules Not Applied, ESLint Config Not Migrated, or VSCode Extension Ignored

  How to fix Biome linter/formatter issues — biome.json configuration, migrating from ESLint and Prettier, VSCode extension setup, CI integration, and rule override syntax.

• Fix: Convex Not Working — Query Not Updating, Mutation Throwing Validation Error, or Action Timing Out

  How to fix Convex backend issues — query/mutation/action patterns, schema validation, real-time reactivity, file storage, auth integration, and common TypeScript type errors.

• Fix: date-fns Not Working — Wrong Timezone Output, Invalid Date, or Locale Not Applied

  How to fix date-fns issues — timezone handling with date-fns-tz, parseISO vs new Date, locale import and configuration, DST edge cases, v3 ESM migration, and common format pattern mistakes.

• Fix: esbuild Not Working — Plugin Errors, CSS Not Processed, or Output Missing After Build

  How to fix esbuild issues — entry points, plugin API, JSX configuration, CSS modules, watch mode, metafile analysis, external packages, and common migration problems from webpack.

• Fix: Hono Not Working — Route Not Matching, Middleware Skipped, or RPC Client Type Mismatch

  How to fix Hono framework issues — routing order, middleware chaining, Hono RPC type inference, Cloudflare Workers bindings, validator integration, and runtime compatibility.

• Fix: Kysely Not Working — Type Errors on Queries, Migration Failing, or Generated Types Not Matching Schema

  How to fix Kysely query builder issues — database interface definition, dialect setup, type-safe joins and subqueries, migration runner, kysely-codegen for generated types, and common TypeScript errors.

• Fix: Lucia Auth Not Working — Session Not Created, Middleware Rejecting Valid Sessions, or OAuth Callback Failing

  How to fix Lucia auth issues — adapter setup, session validation in middleware, cookie configuration, OAuth provider integration, Next.js App Router setup, and Lucia v3 migration.

• Fix: MDX Not Working — Components Not Rendering, Imports Failing, or Frontmatter Not Parsed

  How to fix MDX issues — Next.js App Router setup with @next/mdx and next-mdx-remote, custom component mapping, frontmatter parsing with gray-matter, remark and rehype plugins, and TypeScript configuration.

• Fix: MSW (Mock Service Worker) Not Working — Handlers Not Intercepting, Browser Not Mocking, or v2 Migration Errors

  How to fix Mock Service Worker issues — browser vs Node setup, handler registration, worker start timing, passthrough requests, and common MSW v2 API changes from v1.

• Fix: next-intl Not Working — Translations Missing, Locale Not Detected, or Middleware Redirect Loop

  How to fix next-intl issues — App Router setup with middleware, useTranslations in server and client components, locale detection, pluralization, number and date formatting, and routing configuration.

• Fix: Playwright Not Working — Test Timeout, Selector Not Found, or CI Headless Fails

  How to fix Playwright test issues — locator strategies, auto-waiting, network mocking, flaky tests in CI, trace viewer debugging, and common headless browser setup problems.

• Fix: Recharts Not Working — Chart Not Rendering, Tooltip Missing, or ResponsiveContainer Showing Zero Height

  How to fix Recharts issues — ResponsiveContainer setup, data format for each chart type, custom tooltips, axis configuration, legends, animations, and TypeScript types.

• Fix: RxJS Not Working — Observable Not Emitting, Memory Leak from Unsubscribed Stream, or Operator Behaving Unexpectedly

  How to fix RxJS issues — subscription management, switchMap vs mergeMap vs concatMap, error handling with catchError, Subject types, cold vs hot observables, and Angular async pipe.

• Fix: SolidJS Not Working — Signal Not Updating, Effect Running Twice, or createResource Data Undefined

  How to fix SolidJS reactivity issues — signal access inside JSX, effect dependencies, createResource with loading states, Show and For components, store mutations, and common mistakes coming from React.

• Fix: Supabase Not Working — RLS Policy Blocking Queries, Realtime Not Receiving Updates, or Auth Session Lost

  How to fix Supabase issues — Row Level Security policies, realtime subscriptions, storage permissions, auth session with Next.js, edge functions, and common client configuration mistakes.

• Fix: Tiptap Not Working — Editor Not Rendering, Extensions Missing, or Content Not Saving

  How to fix Tiptap editor issues — useEditor setup in React, StarterKit configuration, custom nodes and marks, SSR with Next.js, collaborative editing, and content serialization.

• Fix: XState Not Working — Machine Not Transitioning, Guards Not Running, or Actor Not Sending Events

  How to fix XState v5 issues — state machine definition, guards and actions typed correctly, useMachine hook, createActor, context updates, child actors, and common v4 to v5 migration errors.

• Fix: Angular Pipe Not Working — Custom Pipe Not Transforming or async Pipe Not Rendering

  How to fix Angular pipe issues — declaring pipes in modules, standalone pipe imports, pure vs impure pipes, async pipe with observables, pipe chaining, and custom pipe debugging.

• Fix: Drizzle ORM Not Working — Schema Out of Sync, Relation Query Fails, or Migration Error

  How to fix Drizzle ORM issues — schema definition, drizzle-kit push vs migrate, relation queries with, transactions, type inference, and common PostgreSQL/MySQL configuration problems.

• Fix: ESLint Config Not Working — Rules Ignored, Flat Config Errors, or Plugin Not Found

  How to fix ESLint configuration issues — flat config vs legacy config, extends conflicts, parser options, plugin resolution, per-directory overrides, and migrating to ESLint 9.

• Fix: Jest Setup File Not Working — setupFilesAfterFramework Not Running or Globals Not Applied

  How to fix Jest setup file issues — setupFilesAfterFramework vs setupFiles, global mocks not applying, @testing-library/jest-dom matchers, module mocking in setup, and TypeScript setup files.

• Fix: NextAuth.js Not Working — Session Null, Callback Errors, or OAuth Redirect Issues

  How to fix NextAuth.js (Auth.js) issues — session undefined in server components, OAuth callback URL mismatch, JWT vs database sessions, middleware protection, and credentials provider.

• Fix: Pinia Store Not Working — State Not Reactive, Actions Not Updating, or Store Not Found

  How to fix Pinia store issues — state reactivity with storeToRefs, getters not updating, actions async patterns, store outside components, SSR hydration, and testing Pinia stores.

• Fix: React Hook Form Not Working — register Not Applying, Validation Not Triggering, or Controller Issues

  How to fix React Hook Form issues — register spread syntax, Controller for UI libraries, validation modes, watch vs getValues, nested fields, and form submission errors.

• Fix: tRPC Not Working — Type Inference Lost, Procedure Not Found, or Context Not Available

  How to fix tRPC issues — router setup, type inference across packages, context injection, middleware, error handling, and common tRPC v10/v11 configuration mistakes.

• Fix: TypeScript Conditional Types Not Working — infer Not Extracting, Distributive Behavior Unexpected, or Type Resolves to never

  How to fix TypeScript conditional type issues — infer keyword usage, distributive conditional types, deferred evaluation, naked type parameters, and common conditional type patterns.

• Fix: TypeScript Discriminated Union Error — Property Does Not Exist or Narrowing Not Working

  How to fix TypeScript discriminated union errors — type guards, exhaustive checks, narrowing with in operator, never type, and common patterns for tagged unions.

• Fix: TypeScript Template Literal Type Error — Type Not Assignable or Inference Fails

  How to fix TypeScript template literal type errors — string combination types, conditional inference, Extract and mapped types with template literals, and common pitfalls.

• Fix: Vue Slot Not Working — Named Slots Not Rendering or Scoped Slot Data Not Accessible

  How to fix Vue 3 slot issues — v-slot syntax, named slots, scoped slots passing data, default slot content, fallback content, and dynamic slot names.

• Fix: Zod Validation Not Working — safeParse Returns Wrong Error, transform Breaks Type, or discriminatedUnion Fails

  How to fix Zod schema validation issues — parse vs safeParse, transform and preprocess, refine for cross-field validation, discriminatedUnion, error formatting, and common schema mistakes.

• Fix: NestJS Swagger UI Not Showing — /api-docs Returns 404 or Blank Page

  How to fix NestJS Swagger UI not displaying — SwaggerModule setup, DocumentBuilder, decorators not appearing, guards blocking the docs route, and Fastify vs Express differences.

• Fix: Next.js Server Action Not Working — Action Not Called or Returns Error

  How to fix Next.js Server Actions — use server directive, form binding, revalidation, error handling, middleware conflicts, and client component limitations.

• Fix: Prisma Enum Not Working — Invalid Enum Value or Enum Not Recognized

  How to fix Prisma enum errors — schema definition, database sync, TypeScript enum type mismatch, filtering by enum, and migrating existing enum values.

• Fix: React Testing Library Not Finding Element — Unable to Find Role or Text

  How to fix React Testing Library query failures — getByRole vs getByText, async queries, accessible names, waitFor patterns, custom queries, and common selector mistakes.

• Fix: Vite Proxy Not Working — API Requests Not Forwarded or 404/502 Errors

  How to fix Vite dev server proxy issues — proxy configuration in vite.config.ts, path rewriting, WebSocket proxying, HTTPS targets, and common misconfigurations.

• Fix: Angular HTTP Interceptor Not Working — Requests Not Intercepted

  How to fix Angular HTTP interceptors not triggering — provideHttpClient setup, functional interceptors, order of interceptors, excluding specific URLs, and error handling.

• Fix: Angular Signals Not Updating — computed() and effect() Not Triggering

  How to fix Angular Signals not updating — signal mutations, computed dependency tracking, effect() cleanup, toSignal() with Observables, and migrating from zone-based change detection.

• Fix: Angular Standalone Component Error — Component is Not a Known Element

  How to fix Angular standalone component errors — imports array, NgModule migration, RouterModule vs RouterLink, CommonModule replacement, and mixing standalone with module-based components.

• Fix: Jest Async Test Timeout — Exceeded 5000ms or Test Never Resolves

  How to fix Jest async test timeouts — missing await, unresolved Promises, done callback misuse, global timeout configuration, fake timers, and async setup/teardown issues.

• Fix: Jest Coverage Not Collected — Files Missing from Coverage Report

  How to fix Jest coverage not collecting all files — collectCoverageFrom config, coverage thresholds, Istanbul ignore comments, ts-jest setup, and Babel transform issues.

• Fix: NestJS Nest can't resolve dependencies — Provider Not Found Error

  How to fix NestJS dependency injection errors — module imports, provider exports, circular dependencies, dynamic modules, and the most common 'can't resolve dependencies' patterns.

• Fix: NestJS ValidationPipe Not Working — class-validator Decorators Ignored

  How to fix NestJS ValidationPipe not validating requests — global pipe setup, class-transformer, whitelist and transform options, custom validators, and DTO inheritance issues.

• Fix: Python mypy Type Error — Incompatible Types and Missing Annotations

  How to fix Python mypy type errors — incompatible types in assignment, missing return type, Optional handling, TypedDict, Protocol, overloads, and common mypy configuration mistakes.

• Fix: React forwardRef Not Working — ref is null or Component Not Exposing Methods

  How to fix React forwardRef issues — ref null on custom components, useImperativeHandle setup, forwardRef with TypeScript, class components, and React 19 ref as prop changes.

• Fix: React Suspense Not Working — Boundary Not Catching or Fallback Not Showing

  How to fix React Suspense boundaries not triggering — lazy() import syntax, use() hook, data fetching libraries, ErrorBoundary vs Suspense, and Next.js loading.tsx.

• Fix: TypeScript Function Overload Error — No Overload Matches This Call

  How to fix TypeScript function overload errors — overload signature compatibility, implementation signature, conditional types as alternatives, method overloads in classes, and common pitfalls.

• Fix: TypeScript Mapped Type Errors — Type is Not Assignable to Mapped Type

  How to fix TypeScript mapped type errors — Partial, Required, Readonly, Record, Pick, Omit, conditional types, template literal types, and distributive behavior.

• Fix: Pinia State Not Reactive — Store Changes Not Updating the Component

  How to fix Pinia store state not updating components — storeToRefs for destructuring, $patch for partial updates, avoiding reactive() wrapping, getters vs computed, and SSR hydration.

• Fix: Angular Form Validation Not Working — Validators Not Triggering

  How to fix Angular form validation not working — Reactive Forms vs Template-Driven, custom validators, async validators, touched/dirty state, and error message display.

• Fix: Angular Lazy Loading Not Working — Routes Not Code-Split

  How to fix Angular lazy loading not working — loadChildren syntax, standalone components, route configuration mistakes, preloading strategies, and debugging bundle splits.

• Fix: Angular RxJS Memory Leak — Subscriptions Not Unsubscribed

  How to fix RxJS memory leaks in Angular — unsubscribing from Observables, takeUntilDestroyed, async pipe, subscription management patterns, and detecting leaks with Chrome DevTools.

• Fix: Jest Fake Timers Not Working — setTimeout and setInterval Not Advancing

  How to fix Jest fake timers not working — useFakeTimers setup, runAllTimers vs advanceTimersByTime, async timers, React testing with act(), and common timer test mistakes.

• Fix: Jest Module Mock Not Working — jest.mock() Has No Effect

  How to fix Jest module mocks not working — hoisting behavior, ES module mocks, factory functions, mockReturnValue vs implementation, and clearing mocks between tests.

• Fix: NestJS Guard Not Working — canActivate Always Passes or Is Never Called

  How to fix NestJS guards not working — applying guards globally vs controller vs method level, JWT AuthGuard, metadata with Reflector, public routes, and guard execution order.

• Fix: NestJS Interceptor Not Triggered — Interceptors Not Running

  How to fix NestJS interceptors not being called — global vs controller vs method binding, response transformation, async interceptors, execution context, and interceptor ordering.

• Fix: Node.js UnhandledPromiseRejection and uncaughtException — Crashing Server

  How to handle Node.js uncaughtException and unhandledRejection events — graceful shutdown, error logging, async error boundaries, and keeping servers alive safely.

• Fix: Prisma N+1 Query Problem — include, select, and Relation Loading

  How to fix the N+1 query problem in Prisma — using include and select for eager loading, fluent API pitfalls, DataLoader integration, and query logging to detect N+1 patterns.

• Fix: Prisma Transaction Error — Transaction Already Closed or Rolled Back

  How to fix Prisma transaction errors — interactive transactions vs $transaction array, error handling and rollback, nested transactions, timeout issues, and isolation levels.

• Fix: React Hydration Error — Text Content Does Not Match

  How to fix React hydration errors — server/client HTML mismatches, useEffect for client-only code, suppressHydrationWarning, dynamic content, and Next.js specific hydration issues.

• Fix: TanStack Query (React Query) Returning Stale Data — Cache Not Updating

  How to fix TanStack Query returning stale cached data — staleTime, invalidateQueries, query key structure, optimistic updates, and cache synchronization after mutations.

• Fix: TypeScript Could Not Find Declaration File — Module Has No Type Information

  How to fix TypeScript 'could not find a declaration file for module' errors — installing @types packages, writing custom .d.ts files, module augmentation, and tsconfig paths.

• Fix: Vue Computed Property Not Updating — Reactivity Not Triggered

  How to fix Vue computed properties not updating — reactive dependency tracking, accessing nested objects, computed setters, watchEffect vs computed, and Vue 3 reactivity pitfalls.

• Fix: Vue v-model Not Working on Custom Components — Prop Not Syncing

  How to fix Vue v-model on custom components — defineModel, modelValue/update:modelValue pattern, multiple v-model bindings, v-model modifiers, and Vue 2 vs Vue 3 differences.

• Fix: Webpack/Vite Path Alias Not Working — Module Not Found with @/ Prefix

  How to fix path alias errors in webpack and Vite — configuring resolve.alias, tsconfig paths, babel-plugin-module-resolver, Vite alias configuration, and Jest moduleNameMapper.

• Fix: Angular Change Detection Not Working — View Not Updating

  How to fix Angular change detection issues — OnPush strategy not triggering, async pipe, markForCheck vs detectChanges, zone.js and zoneless patterns, and manual change detection triggers.

• Fix: CSS Container Query Not Working — @container and container-type Issues

  How to fix CSS container queries not working — setting container-type correctly, understanding containment scope, fixing @container syntax, and handling browser support and specificity issues.

• Fix: Express Async Error Not Being Caught — Unhandled Promise Rejection

  How to fix Express async route handlers not passing errors to the error middleware — wrapping async routes, using express-async-errors, global error handlers, and Node.js unhandledRejection events.

• Fix: Jest Cannot Transform ES Modules — SyntaxError: Cannot use import statement

  How to fix Jest failing with 'Cannot use import statement outside a module' — configuring Babel transforms, using experimental VM modules, migrating to Vitest, and handling ESM-only packages.

• Fix: NestJS Circular Dependency — forwardRef and Module Design

  How to fix NestJS circular dependency errors — using forwardRef, restructuring module dependencies, extracting shared services, and understanding the NestJS module system.

• Fix: Next.js App Router Fetch Not Caching or Always Stale

  How to fix Next.js App Router fetch caching issues — understanding cache behavior, revalidation with next.revalidate, opting out with no-store, cache tags, and debugging stale data.

• Fix: React Server Components Error — useState, Event Handlers, and Client Boundary Issues

  How to fix React Server Components errors — useState and hooks in server components, missing 'use client' directive, async component patterns, serialization errors, and client/server boundary mistakes.

• Fix: Redux State Not Updating — Component Not Re-rendering

  How to fix Redux state not updating in components — mutating state directly, stale selectors, missing immer patterns in Redux Toolkit, useSelector mistakes, and debugging with Redux DevTools.

• Fix: Svelte Store Not Updating — Reactive Store Issues

  How to fix Svelte store not updating the UI — writable vs readable stores, derived stores, subscribe pattern, store mutation vs assignment, and custom store patterns.

• Fix: TypeORM QueryFailedError and Entity Not Found

  How to fix TypeORM QueryFailedError, entity not found errors, relation issues, missing migrations, and connection configuration problems in Node.js and NestJS applications.

• Fix: Vue Router Navigation Guard Not Working — beforeEach and Route Guards

  How to fix Vue Router navigation guards not working — beforeEach, beforeEnter, in-component guards, async guards, redirect loops, and route meta authentication patterns.

• Fix: Axios Network Error — Request Failed with Status Code 0

  How to fix Axios 'Network Error' with no status code — CORS blocks, SSL certificate issues, request timeout, no internet connection, and debugging with interceptors.

• Fix: ESLint no-unused-vars False Positives and Configuration

  How to fix ESLint no-unused-vars false positives — TypeScript types, destructuring ignores, React imports, function arguments, and configuring the rule to match your codebase patterns.

• Fix: Jest Snapshot Outdated — 1 snapshot obsolete

  How to fix Jest snapshot failures — updating outdated snapshots, removing obsolete ones, fixing inline snapshots, preventing brittle snapshot tests, and managing snapshots in CI.

• Fix: Next.js CORS Error on API Routes

  How to fix CORS errors in Next.js API routes — adding Access-Control headers, handling preflight OPTIONS requests, configuring next.config.js headers, and avoiding common proxy mistakes.

• Fix: Prisma Unique Constraint Failed on the Fields

  How to fix Prisma's 'Unique constraint failed on the fields' error — finding which field caused it, handling upserts, race conditions, and bulk insert deduplication.

• Fix: React useEffect Runs Twice in Development

  Why React useEffect runs twice in development with Strict Mode, how to handle the double invocation correctly, when to add cleanup functions, and when the double-run actually reveals a real bug.

• Fix: TypeScript Decorators Not Working (experimentalDecorators)

  How to fix TypeScript decorators not applying — experimentalDecorators not enabled, emitDecoratorMetadata missing, reflect-metadata not imported, and decorator ordering issues.

• Fix: TypeScript Enum Not Working — const enum, isolatedModules, and Runtime Issues

  How to fix TypeScript enum problems — const enum with isolatedModules, enums not available at runtime, string vs numeric enums, and migrating to union types or as const objects.

• Fix: Vite Environment Variables Not Working

  How to fix Vite environment variables showing as undefined — missing VITE_ prefix, wrong .env file for the mode, import.meta.env vs process.env, TypeScript types, and SSR differences.

• Fix: Next.js Middleware Not Running (middleware.ts Not Intercepting Requests)

  How to fix Next.js middleware not executing — wrong file location, matcher config errors, middleware not intercepting API routes, and how to debug middleware execution in Next.js 13 and 14.

• Fix: TypeScript isolatedModules Errors (const enum, type-only imports)

  How to fix TypeScript isolatedModules errors — why const enum fails with Babel and Vite, how to replace const enum, fix re-exported types, and configure isolatedModules correctly for your build tool.

• Fix: Vitest Setup Not Working (setupFiles, Mocks, and Global Config Issues)

  How to fix Vitest configuration not taking effect — why setupFiles don't run, globals are undefined, mocks don't work, and how to configure Vitest correctly for React, Vue, and Node.js projects.

• Fix: ESLint import/no-unresolved Error (Module Exists but ESLint Can't Find It)

  How to fix ESLint's import/no-unresolved errors when modules actually resolve correctly — configure eslint-import-resolver-typescript, fix path alias settings, and handle node_modules that ESLint cannot find.

• Fix: jest.mock() Not Working — Module Not Being Replaced in Tests

  How to fix jest.mock() not intercepting module calls — why mocks are ignored, how to correctly mock ES modules, default exports, named exports, and fix hoisting issues in Jest tests.

• Fix: Next.js Build Failed (next build Errors and How to Fix Them)

  How to fix Next.js build failures — TypeScript errors blocking production builds, module resolution failures, missing environment variables, static generation errors, and common next build crash causes.

• Fix: JavaScript NaN === NaN Returns false (NaN Comparison Bugs)

  How to fix JavaScript NaN comparison bugs — why NaN !== NaN, the difference between isNaN() and Number.isNaN(), and how to correctly check for NaN in conditionals and array operations.

• Fix: TypeScript Generic Type Constraint Errors

  How to fix TypeScript generic constraint errors — Type 'X' does not satisfy the constraint 'Y', generic inference failures, constrained generics with extends, and conditional types.

• Fix: TypeScript Path Aliases Not Working (Cannot Find Module '@/...')

  How to fix TypeScript path aliases not resolving — tsconfig paths configured but imports still fail at runtime, in Jest, or after building with webpack, Vite, or ts-node.

• Fix: Angular ExpressionChangedAfterItHasBeenCheckedError

  How to fix ExpressionChangedAfterItHasBeenCheckedError in Angular caused by change detection timing issues, lifecycle hooks, async pipes, and parent-child data flow.

• Fix: Angular NullInjectorError: No provider for X

  How to fix Angular NullInjectorError No provider for service caused by missing providers, wrong module imports, standalone components, and lazy-loaded module issues.

• Fix: SyntaxError: Cannot use import statement outside a module

  How to fix 'SyntaxError: Cannot use import statement outside a module' in Node.js, TypeScript, Jest, and browsers by configuring ESM, package.json type, and transpiler settings.

• Fix: TypeError: x is not a function

  How to fix JavaScript TypeError is not a function caused by wrong variable types, missing imports, overwritten variables, incorrect method names, and callback issues.

• Fix: TypeScript Argument of type 'X' is not assignable to parameter of type 'Y' (TS2345)

  How to fix TypeScript error TS2345 Argument of type is not assignable to parameter of type, covering null narrowing, union types, generics, callback types, type widening, enums, and React event handlers.

• Fix: TypeScript error TS2304: Cannot find name 'x'

  How to fix TypeScript Cannot find name error caused by missing type declarations, missing imports, wrong tsconfig settings, global types, and DOM API usage.

• Fix: TypeScript Could not find a declaration file for module (TS7016)

  How to fix the TypeScript TS7016 error 'Could not find a declaration file for module' by installing @types packages, creating declaration files, and configuring tsconfig.json.

• Fix: TypeScript Property does not exist on type (TS2339)

  How to fix TypeScript error TS2339 'Property does not exist on type'. Covers missing interface properties, type narrowing, optional chaining, intersection types, index signatures, type assertions, type guards, window augmentation, and discriminated unions.

• Fix: TypeScript Type 'X | undefined' is not assignable to type 'X'

  How to fix TypeScript strict null checks error Type X undefined is not assignable caused by optional values, nullable types, missing guards, and strictNullChecks.

• Fix: TypeScript Cannot Find Module or Its Corresponding Type Declarations

  How to fix the TypeScript error 'Cannot find module' or 'Could not find a declaration file for module' with proper type declarations and tsconfig settings.

• Fix: ESLint Parsing error: Unexpected token (JSX, TypeScript, ES modules)

  How to fix ESLint 'Parsing error: Unexpected token' for JSX, TypeScript, and ES module syntax by configuring the correct parser, parserOptions, and ESLint config format.

• Fix: Module parse failed: Unexpected token (Webpack / Vite / esbuild)

  How to fix 'Module parse failed: Unexpected token' in Webpack, Vite, and esbuild by configuring the correct loaders and transforms for JSX, TypeScript, CSS, JSON, and other file types.

• Fix: TS2322 Type 'X' is not assignable to type 'Y'

  How to fix TypeScript error TS2322 'Type is not assignable to type'. Covers literal types vs general types, string vs String, union types, interface compatibility, generic constraints, readonly arrays, excess property checking, discriminated unions, type assertions, type widening and narrowing, React event handlers, Promise return types, and enum mismatches.

• Fix: SyntaxError: Unexpected token < in JSON at position 0

  How to fix 'Unexpected token in JSON at position 0', 'JSON.parse: unexpected character', and 'Unexpected end of JSON input' in JavaScript and TypeScript. Covers API returning HTML instead of JSON, Content-Type mismatches, fetch URL typos, invalid JSON syntax, BOM characters, CORS proxies, and debugging with response.text().

• Fix: TS2532 Object is possibly 'undefined' / Object is possibly 'null'

  How to fix TypeScript errors TS2532 'Object is possibly undefined', TS18048 'Object is possibly undefined', and 'Object is possibly null'. Covers optional chaining, nullish coalescing, type narrowing, non-null assertion, type guards, strictNullChecks, Array.find, Map.get, React useRef, and more.

• Fix: Module not found: Can't resolve / Cannot find module or its corresponding type declarations

  How to fix 'Module not found: Can't resolve' in webpack, Vite, and React, and 'Cannot find module or its corresponding type declarations' in TypeScript. Covers missing packages, wrong import paths, case sensitivity, path aliases, node_modules corruption, monorepo hoisting, barrel files, and asset imports.

• Fix: [vite] Internal server error: Failed to resolve import

  How to fix Vite's 'Failed to resolve import' error, including 'Does the file exist?', 'Optimized dependency needs to be force included', 'Pre-transform error', and '504 (Outdated Optimize Dep)'. Covers missing packages, path aliases, optimizeDeps, cache clearing, and CJS/monorepo edge cases.

• Fix: TypeError: Cannot read properties of undefined (reading 'xxx')

  How to fix 'TypeError: Cannot read properties of undefined', 'Cannot read property of undefined', and 'Cannot read properties of null' in JavaScript, TypeScript, and React. Covers optional chaining, async data fetching, destructuring, and nested object access.

• Fix: Error Cannot find module in Node.js (MODULE_NOT_FOUND)

  How to fix 'Error: Cannot find module' and 'MODULE_NOT_FOUND' in Node.js. Covers missing packages, wrong import paths, node_modules issues, TypeScript moduleResolution, ESM vs CJS, and monorepo hoisting.

Node.js Runtime (87)

• Fix: mise Not Working — Shell Activation, .tool-versions, Plugin Install, and Python venv

  How to fix mise (formerly rtx) errors — activation hook not running, tool not found after install, .tool-versions vs .mise.toml, Python venv integration, idiomatic env loading, and trust prompts.

• Fix: Mongoose Not Working — Connection Options Removed, strictQuery, populate, and Lean Queries

  How to fix Mongoose errors — useNewUrlParser removed, strictQuery default flip, populate returning null, lean() losing methods, discriminator setup, transaction sessions, and TypeScript Document types.

• Fix: Node.js fs.watch Not Working — Cross-Platform Quirks, chokidar Migration, Recursive Watch

  How to fix Node.js file watching — fs.watch unreliable on Linux, missing events on save, recursive watch on Windows/macOS, chokidar polling fallback, ignoring patterns, debouncing, and EMFILE errors.

• Fix: Node.js Stream pipeline() Not Working — Backpressure, Error Propagation, AbortSignal, and Web Streams Interop

  How to fix Node.js stream/promises pipeline errors — uncaught stream errors, backpressure ignored, AbortSignal not propagating, async iterators in pipeline, Transform stream object mode, and converting between Node and Web Streams.

• Fix: Node.js Test Runner Not Working — node --test, TypeScript, Mocks, Coverage, and Watch Mode

  How to fix Node.js built-in test runner errors — node --test not finding files, ESM vs CJS imports, TypeScript with --experimental-strip-types, mock.method isolation, coverage reporting, and watch mode setup.

• Fix: tsx Not Working — ESM Imports, Watch Mode, Path Aliases, and node --import tsx

  How to fix tsx (TypeScript executor) errors — Cannot find module after upgrade, ESM .js extension required, tsconfig paths not respected, watch mode not restarting, --import vs --loader, VS Code debugger setup.

• Fix: pnpm Workspace Not Working — workspace:* Protocol, Catalog, Filters, and Hoisting Issues

  How to fix pnpm workspace errors — workspace:* not resolving, catalog versions out of sync, --filter not matching, peer deps unmet across packages, shamefully-hoist trade-offs, and publishConfig for releases.

• Fix: Fastify Not Working — 404, Plugin Encapsulation, and Schema Validation Errors

  How to fix Fastify issues — route 404 from plugin encapsulation, reply already sent, FST_ERR_VALIDATION, request.body undefined, @fastify/cors, hooks not running, and TypeScript type inference.

• Fix: Puppeteer Not Working — Navigation Timeout, Chrome Not Found, and Target Closed

  How to fix Puppeteer errors — navigation timeout exceeded, failed to launch browser process in Docker and CI, element not found, page crashed Target closed, memory leaks from unclosed pages, and waiting for dynamic content.

• Fix: Meilisearch Not Working — Search Returns No Results, Index Not Found, or API Key Errors

  How to fix Meilisearch issues — index setup, document indexing, search configuration, filtering, facets, typo tolerance, and self-hosted deployment.

• Fix: Nodemailer Not Working — Emails Not Sending, SMTP Auth Failing, or Gmail Blocking

  How to fix Nodemailer issues — SMTP configuration, Gmail OAuth2, TLS errors, connection timeouts, email not delivered, and using with Next.js or Express.

• Fix: Temporal Not Working — Workflows Not Starting, Activities Failing, or Worker Not Connecting

  How to fix Temporal issues — worker setup, workflow and activity errors, schedule configuration, versioning, and self-hosted Temporal Server deployment.

• Fix: Strapi Not Working — API Returns 403, Content Not Appearing, or Plugin Errors

  How to fix Strapi v5 issues — permissions, content types, REST and GraphQL APIs, media uploads, webhooks, plugins, and deployment configuration.

• Fix: AWS SQS Not Working — Messages Not Received, Duplicate Processing, or DLQ Filling Up

  How to fix AWS SQS issues — visibility timeout, message not delivered, duplicate messages, Dead Letter Queue configuration, FIFO queue ordering, and Lambda trigger problems.

• Fix: Bun Not Working — Node.js Module Incompatible, Native Addon Fails, or bun test Errors

  How to fix Bun runtime issues — Node.js API compatibility, native addons (node-gyp), Bun.serve vs Node http, bun test differences from Jest, and common package incompatibilities.

• Fix: Drizzle ORM Not Working — Schema Out of Sync, Relation Query Fails, or Migration Error

  How to fix Drizzle ORM issues — schema definition, drizzle-kit push vs migrate, relation queries with, transactions, type inference, and common PostgreSQL/MySQL configuration problems.

• Fix: gRPC Error Not Working — Status Codes, Connection Failed, or Deadline Exceeded

  How to fix gRPC errors — UNAVAILABLE connection errors, DEADLINE_EXCEEDED, UNIMPLEMENTED, TLS setup, interceptors for error handling, and status code mapping.

• Fix: OpenTelemetry Not Working — Traces Not Appearing, Spans Missing, or Exporter Connection Refused

  How to fix OpenTelemetry issues — SDK initialization order, auto-instrumentation setup, OTLP exporter configuration, context propagation, and missing spans in Node.js, Python, and Java.

• Fix: tRPC Not Working — Type Inference Lost, Procedure Not Found, or Context Not Available

  How to fix tRPC issues — router setup, type inference across packages, context injection, middleware, error handling, and common tRPC v10/v11 configuration mistakes.

• Fix: NestJS Swagger UI Not Showing — /api-docs Returns 404 or Blank Page

  How to fix NestJS Swagger UI not displaying — SwaggerModule setup, DocumentBuilder, decorators not appearing, guards blocking the docs route, and Fastify vs Express differences.

• Fix: Node.js Stream Error — Pipe Not Working, Backpressure, or Premature Close

  How to fix Node.js stream issues — pipe and pipeline errors, backpressure handling, Transform streams, async iteration, error propagation, and common stream anti-patterns.

• Fix: Prisma Enum Not Working — Invalid Enum Value or Enum Not Recognized

  How to fix Prisma enum errors — schema definition, database sync, TypeScript enum type mismatch, filtering by enum, and migrating existing enum values.

• Fix: Express Rate Limit Not Working — express-rate-limit Requests Not Throttled

  How to fix Express rate limiting not working — middleware order, trust proxy for reverse proxies, IP detection, store configuration, custom key generation, and bypassing issues.

• Fix: GraphQL Error Handling Not Working — Errors Not Returned or Always 200 OK

  How to fix GraphQL error handling — error extensions, partial data with errors, Apollo formatError, custom error classes, client-side error detection, and network vs GraphQL errors.

• Fix: GraphQL Subscription Not Updating — WebSocket Connection Not Receiving Events

  How to fix GraphQL subscriptions not receiving updates — WebSocket setup, subscription protocol, Apollo Client config, server-side pub/sub, authentication over WebSocket, and reconnection.

• Fix: MongoDB Schema Validation Error — Document Failed Validation

  How to fix MongoDB schema validation errors — $jsonSchema rules, required fields, type mismatches, enum constraints, bypassing validation for migrations, and Mongoose schema conflicts.

• Fix: NestJS Nest can't resolve dependencies — Provider Not Found Error

  How to fix NestJS dependency injection errors — module imports, provider exports, circular dependencies, dynamic modules, and the most common 'can't resolve dependencies' patterns.

• Fix: NestJS ValidationPipe Not Working — class-validator Decorators Ignored

  How to fix NestJS ValidationPipe not validating requests — global pipe setup, class-transformer, whitelist and transform options, custom validators, and DTO inheritance issues.

• Fix: Prisma Connection Pool Exhausted — Can't Acquire Connection from Pool

  How to fix Prisma connection pool errors — pool size configuration, connection leaks, serverless deployments, singleton pattern, query timeout, and pgBouncer integration.

• Fix: NestJS Guard Not Working — canActivate Always Passes or Is Never Called

  How to fix NestJS guards not working — applying guards globally vs controller vs method level, JWT AuthGuard, metadata with Reflector, public routes, and guard execution order.

• Fix: NestJS Interceptor Not Triggered — Interceptors Not Running

  How to fix NestJS interceptors not being called — global vs controller vs method binding, response transformation, async interceptors, execution context, and interceptor ordering.

• Fix: Node.js UnhandledPromiseRejection and uncaughtException — Crashing Server

  How to handle Node.js uncaughtException and unhandledRejection events — graceful shutdown, error logging, async error boundaries, and keeping servers alive safely.

• Fix: Prisma N+1 Query Problem — include, select, and Relation Loading

  How to fix the N+1 query problem in Prisma — using include and select for eager loading, fluent API pitfalls, DataLoader integration, and query logging to detect N+1 patterns.

• Fix: Prisma Transaction Error — Transaction Already Closed or Rolled Back

  How to fix Prisma transaction errors — interactive transactions vs $transaction array, error handling and rollback, nested transactions, timeout issues, and isolation levels.

• Fix: Redis Pub/Sub Not Working — Messages Not Received by Subscribers

  How to fix Redis Pub/Sub issues — subscriber not receiving messages, channel name mismatches, connection handling, pattern subscriptions, and scaling with multiple processes.

• Fix: Socket.IO CORS Error — Cross-Origin Connection Blocked

  How to fix Socket.IO CORS errors — server-side CORS configuration, credential handling, polling vs WebSocket transport, proxy setup, and common connection failures.

• Fix: Express Async Error Not Being Caught — Unhandled Promise Rejection

  How to fix Express async route handlers not passing errors to the error middleware — wrapping async routes, using express-async-errors, global error handlers, and Node.js unhandledRejection events.

• Fix: GraphQL N+1 Query Problem — DataLoader and Batching

  How to fix the GraphQL N+1 query problem — understanding why it happens, implementing DataLoader for batching, using query complexity limits, and selecting efficient resolver patterns.

• Fix: Jest Cannot Transform ES Modules — SyntaxError: Cannot use import statement

  How to fix Jest failing with 'Cannot use import statement outside a module' — configuring Babel transforms, using experimental VM modules, migrating to Vitest, and handling ESM-only packages.

• Fix: NestJS Circular Dependency — forwardRef and Module Design

  How to fix NestJS circular dependency errors — using forwardRef, restructuring module dependencies, extracting shared services, and understanding the NestJS module system.

• Fix: Node.js JavaScript Heap Out of Memory

  How to fix Node.js 'JavaScript heap out of memory' — increasing heap size, finding memory leaks with heap snapshots, fixing common leak patterns, and stream-based processing for large data.

• Fix: TypeORM QueryFailedError and Entity Not Found

  How to fix TypeORM QueryFailedError, entity not found errors, relation issues, missing migrations, and connection configuration problems in Node.js and NestJS applications.

• Fix: Express req.body Is undefined

  How to fix req.body being undefined in Express — missing body-parser middleware, wrong Content-Type header, middleware order issues, and multipart form data handling.

• Fix: Prisma Unique Constraint Failed on the Fields

  How to fix Prisma's 'Unique constraint failed on the fields' error — finding which field caused it, handling upserts, race conditions, and bulk insert deduplication.

• Fix: Node.js Crashing with UnhandledPromiseRejection (--unhandled-rejections)

  How to fix Node.js UnhandledPromiseRejectionWarning and process crashes — why unhandled promise rejections crash Node.js 15+, how to add global handlers, find the source of the rejection, and fix async error handling.

• Fix: Mongoose ValidationError — Document Failed to Save

  How to fix Mongoose ValidationError when saving documents — required field errors, type cast failures, custom validator errors, and how to handle validation in Express APIs properly.

• Fix: pnpm Peer Dependency Errors (Missing or Incompatible Peer Dependencies)

  How to fix pnpm peer dependency errors — why pnpm is stricter than npm about peer deps, how to resolve missing peers, configure peerDependencyRules, and handle incompatible version ranges.

• Fix: Socket.IO Not Connecting (CORS, Transport, and Namespace Errors)

  How to fix Socket.IO connection failures — CORS errors, transport fallback issues, wrong namespace, server not emitting to the right room, and how to debug Socket.IO connections in production.

• Fix: Prisma Migration Failed (migrate dev / migrate deploy Errors)

  How to fix Prisma migration errors — migrate dev failing with schema drift, migrate deploy errors in production, database out of sync, and how to safely reset or resolve migration conflicts.

• Fix: Stripe Webhook Signature Verification Failed

  How to fix Stripe webhook signature verification errors — why Stripe-Signature header validation fails, how to correctly pass the raw request body, and how to debug webhook delivery in the Stripe dashboard.

• Fix: EMFILE Too Many Open Files / ulimit Error on Linux

  How to fix EMFILE too many open files errors on Linux and Node.js — caused by low ulimit file descriptor limits, file handle leaks, and how to increase limits permanently.

• Fix: Nginx WebSocket Proxy Not Working (101 Switching Protocols Failed)

  How to fix Nginx WebSocket proxying not working — 101 Switching Protocols fails, connections drop after 60 seconds, missing Upgrade headers, and SSL WebSocket configuration.

• Fix: CORS Not Working in Express (Access-Control-Allow-Origin Missing)

  How to fix CORS errors in Express.js — cors middleware not applying, preflight OPTIONS requests failing, credentials not allowed, and specific origin whitelisting issues.

• Fix: TypeScript Path Aliases Not Working (Cannot Find Module '@/...')

  How to fix TypeScript path aliases not resolving — tsconfig paths configured but imports still fail at runtime, in Jest, or after building with webpack, Vite, or ts-node.

• Fix: UnhandledPromiseRejectionWarning / UnhandledPromiseRejection

  How to fix UnhandledPromiseRejectionWarning in Node.js and unhandled promise rejection errors in JavaScript caused by missing catch handlers, async/await mistakes, and event emitter errors.

• Fix: Jest Timeout — Exceeded timeout of 5000ms for a test

  How to fix Jest 'Exceeded timeout of 5000ms for a test' errors caused by unresolved promises, missing done callbacks, async/await mistakes, and slow database or network calls in tests.

• Fix: ECONNRESET Socket Hang Up Error in Node.js

  How to fix the ECONNRESET and socket hang up errors in Node.js caused by server timeouts, keep-alive misconfiguration, proxy issues, large request bodies, SSL/TLS failures, and connection pool exhaustion.

• Fix: SyntaxError: Cannot use import statement outside a module

  How to fix 'SyntaxError: Cannot use import statement outside a module' in Node.js, TypeScript, Jest, and browsers by configuring ESM, package.json type, and transpiler settings.

• Fix: Express Cannot GET /route (404 Not Found)

  How to fix Express.js Cannot GET route 404 error caused by wrong route paths, missing middleware, route order issues, static files, and router mounting problems.

• Fix: FATAL ERROR: Reached heap limit Allocation failed - JavaScript heap out of memory

  How to fix the JavaScript heap out of memory error by increasing Node.js memory limits, fixing memory leaks, and optimizing builds in webpack, Vite, and Docker.

• Fix: Node.js ERR_MODULE_NOT_FOUND - Cannot find module

  How to fix Node.js ERR_MODULE_NOT_FOUND when using ES modules, covering missing file extensions, directory imports, package.json exports, TypeScript paths, and ESM resolution differences.

• Fix: npm ERR! enoent ENOENT: no such file or directory

  How to fix the npm ENOENT no such file or directory error caused by missing package.json, wrong directory, corrupted node_modules, broken symlinks, and npm cache issues.

• Fix: npm ERR! ENOTEMPTY: directory not empty, rename

  How to fix npm ENOTEMPTY directory not empty error caused by corrupted cache, concurrent npm operations, stale node_modules, and Windows file locking issues.

• Fix: npm WARN deprecated — inflight, glob, rimraf, and Other Package Warnings

  npm WARN deprecated [email protected], [email protected], [email protected], @humanwhocodes — which warnings are safe to ignore, which need fixing, and exact steps to silence each one.

• Fix: Error: error:0308010C:digital envelope routines::unsupported

  How to fix the Node.js digital envelope routines unsupported error caused by OpenSSL 3.0 changes in Node.js 17+, with solutions for webpack, Vite, React, and Angular.

• Fix: npm ERR! cb() never called

  Resolve npm's cb() never called error by clearing cache, fixing network issues, updating npm, and resolving corrupted package-lock.json files.

• Fix: .env File Not Loading – dotenv Variables Are Undefined in Node.js, Python, or Docker

  How to fix .env files not being loaded by dotenv, Next.js, Vite, Django, or Docker Compose, including wrong file path, missing dotenv.config(), and variable naming issues.

• Fix: Yarn Integrity Check Failed – Expected and Got Different Results

  How to fix the Yarn error 'integrity check failed' or 'Lockfile does not satisfy expected package' caused by corrupted cache, outdated lockfile, or version mismatches.

• Fix: CORS Error with Credentials – Access-Control-Allow-Credentials and Wildcard Origin

  How to fix CORS errors when using cookies or Authorization headers, including 'Access-Control-Allow-Credentials' and wildcard origin conflicts.

• Fix: npm audit Found Vulnerabilities – How to Fix and Manage Security Issues

  How to fix npm audit vulnerabilities including high and critical severity issues, dependency conflicts, and when to use npm audit fix --force safely.

• Fix: Webpack Module Not Found – Can't Resolve '<module>' in '<directory>'

  How to fix the Webpack error 'Module not found: Error: Can't resolve' caused by missing packages, wrong paths, aliases, or extension resolution issues.

• Fix: TypeScript Cannot Find Module or Its Corresponding Type Declarations

  How to fix the TypeScript error 'Cannot find module' or 'Could not find a declaration file for module' with proper type declarations and tsconfig settings.

• Fix: Redis ECONNREFUSED – Connection Refused on localhost:6379

  How to fix the Redis ECONNREFUSED error when your application cannot connect to the Redis server on localhost:6379 or a remote host. Covers Redis not running, wrong host/port, Docker networking, firewall, AUTH required, maxclients, and TLS configuration.

• Fix: EACCES: permission denied, mkdir / open / unlink (Node.js)

  How to fix EACCES permission denied errors in Node.js for mkdir, open, unlink, and scandir operations, covering npm global installs, Docker, NVM, CI/CD, and filesystem permissions.

• Fix: ENOSPC: System limit for number of file watchers reached

  How to fix the ENOSPC file watchers error on Linux by increasing the inotify watch limit, configuring VS Code, optimizing watched files, and handling Docker/WSL edge cases.

• Fix: npm ERR! code ELIFECYCLE (errno 1, Failed at script)

  How to fix npm ERR! code ELIFECYCLE, npm ERR! errno 1, and npm ERR! Failed at the script errors. Covers reading the real error, node_modules corruption, node-gyp failures, wrong Node version, memory issues, postinstall failures, Windows-specific fixes, and more.

• Fix: MongoServerError: bad auth / MongoNetworkError: connect ECONNREFUSED / MongooseServerSelectionError

  How to fix MongoDB 'MongoServerError: bad auth Authentication failed', 'MongoNetworkError: connect ECONNREFUSED 127.0.0.1:27017', and 'MongooseServerSelectionError' connection errors. Covers MongoDB not running, connection string format, Atlas network access, Docker networking, authentication, DNS/SRV issues, TLS/SSL, and Mongoose options.

• Fix: Error: Process completed with exit code 1 (GitHub Actions)

  How to fix 'Process completed with exit code 1' and other GitHub Actions workflow failures. Covers reading logs, exit codes, Node.js/Python/Docker step failures, secrets and environment variables, GITHUB_TOKEN permissions, checkout issues, caching, timeouts, self-hosted runners, matrix strategy, and artifacts.

• Fix: SSL certificate problem: unable to get local issuer certificate

  How to fix 'SSL certificate problem: unable to get local issuer certificate', 'CERT_HAS_EXPIRED', 'ERR_CERT_AUTHORITY_INVALID', and 'self signed certificate in certificate chain' errors in Git, curl, Node.js, Python, Docker, and more. Covers CA certificates, corporate proxies, Let's Encrypt, certificate chains, and self-signed certs.

• Fix: ERR_CONNECTION_REFUSED (localhost refused to connect)

  How to fix 'ERR_CONNECTION_REFUSED', 'localhost refused to connect', and 'This site can't be reached' errors when accessing localhost in Chrome, Firefox, and Edge. Covers dev servers, port issues, 0.0.0.0 vs 127.0.0.1, Docker port mapping, WSL2, firewalls, and more.

• Fix: npm ERR! Missing script: "start"

  How to fix "npm ERR! Missing script" for start, dev, build, and test. Covers adding scripts to package.json, common framework configurations for React, Next.js, Vite, Angular, Express, and Nest.js.

• Fix: process.env.VARIABLE_NAME Is Undefined (Node.js, React, Next.js, Vite)

  How to fix 'process.env.VARIABLE_NAME is undefined' and environment variables not loading from .env files in Node.js, React, Next.js, Vite, and Docker.

• Fix: Port 3000 Is Already in Use (EADDRINUSE)

  How to fix 'port 3000 is already in use', 'EADDRINUSE', and 'address already in use :::3000' errors in Node.js, React, Next.js, and other frameworks on macOS, Linux, and Windows.

• Fix: npm ERR! ERESOLVE unable to resolve dependency tree

  How to fix the ERESOLVE unable to resolve dependency tree error in npm. Covers root causes, peer dependency conflicts, --legacy-peer-deps, --force, npm overrides, and edge cases with React 18, TypeScript, and monorepos.

• Fix: EACCES permission denied when installing npm packages globally

  How to fix 'Error: EACCES: permission denied, access /usr/local/lib/node_modules' when running npm install -g on macOS or Linux. Multiple solutions ranked by recommendation.

• Fix: Error Cannot find module in Node.js (MODULE_NOT_FOUND)

  How to fix 'Error: Cannot find module' and 'MODULE_NOT_FOUND' in Node.js. Covers missing packages, wrong import paths, node_modules issues, TypeScript moduleResolution, ESM vs CJS, and monorepo hoisting.

• Fix: Access to fetch has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header

  How to fix 'Access to fetch at ... from origin ... has been blocked by CORS policy: No Access-Control-Allow-Origin header is present on the requested resource' in JavaScript. Covers Express, Django, Flask, Spring Boot, ASP.NET, nginx, Apache, dev proxies, preflight requests, credentials, and edge cases.

Package Managers (25)

• Fix: Bun Bundler Not Working — Targets, Format, Externals, Macros, and Code Splitting

  How to fix bun build errors — target (browser/bun/node) mismatch, format esm/cjs/iife, externals not respected, Bun macros at compile time, splitting and chunks, plugin API, and Bun.build vs CLI.

• Fix: Bun Shell Not Working — $ Template Quoting, Pipes, Exit Codes, and Cross-Platform Scripts

  How to fix Bun Shell errors — $ template auto-escape vs raw strings, piping with pipe() vs |, throws on non-zero exit, cwd/env scoping, glob expansion differences, and Windows path handling.

• Fix: Bun Test Not Working — Module Mocking, DOM Setup, Coverage, and Watch Mode

  How to fix Bun test runner issues — mock.module not isolating, happy-dom setup for DOM tests, --coverage missing files, timer mocks, snapshot updates, TypeScript path aliases, and preload files.

• Fix: Hono RPC Not Working — Client Type Inference, AppType Export, Validators, and Path Params

  How to fix Hono RPC client errors — hc<AppType> showing any, validator types not flowing, app.route chaining loses types, monorepo type import, path param typing, JSON body validation, and streaming.

• Fix: pnpm Workspace Not Working — workspace:* Protocol, Catalog, Filters, and Hoisting Issues

  How to fix pnpm workspace errors — workspace:* not resolving, catalog versions out of sync, --filter not matching, peer deps unmet across packages, shamefully-hoist trade-offs, and publishConfig for releases.

• Fix: Changesets Not Working — Version Not Bumping, Changelog Empty, or GitHub Action Failing

  How to fix @changesets/cli issues — changeset creation, version bumping, changelog generation, monorepo support, npm publishing, and GitHub Actions automation.

• Fix: publint Not Working — Package Exports Invalid, Types Not Found, or Dual Package Errors

  How to fix publint package validation issues — exports field configuration, dual ESM/CJS packaging, type resolution, main/module/types fields, files array, and common packaging mistakes.

• Fix: tsup Not Working — Build Failing, Types Not Generated, or ESM/CJS Output Wrong

  How to fix tsup bundler issues — entry points, dual ESM/CJS output, TypeScript declaration files, external dependencies, tree shaking, and package.json exports configuration.

• Fix: unbuild Not Working — Build Output Empty, Stub Mode Failing, or Rollup Errors

  How to fix unbuild issues — build configuration, stub mode for development, ESM and CJS output, TypeScript declarations, external dependencies, and monorepo workspace builds.

• Fix: pnpm Peer Dependency Errors (Missing or Incompatible Peer Dependencies)

  How to fix pnpm peer dependency errors — why pnpm is stricter than npm about peer deps, how to resolve missing peers, configure peerDependencyRules, and handle incompatible version ranges.

• Fix: npm ERR! enoent ENOENT: no such file or directory

  How to fix the npm ENOENT no such file or directory error caused by missing package.json, wrong directory, corrupted node_modules, broken symlinks, and npm cache issues.

• Fix: npm ERR! code E404 – Not Found (package not found in registry)

  How to fix npm ERR code E404 not found error caused by typos, private registries, scoped packages, deleted packages, and authentication issues.

• Fix: npm ERR! ENOTEMPTY: directory not empty, rename

  How to fix npm ENOTEMPTY directory not empty error caused by corrupted cache, concurrent npm operations, stale node_modules, and Windows file locking issues.

• Fix: npm ERR! Could not resolve peer dependency conflict

  How to fix the npm ERR! Could not resolve peer dependency conflict error. Covers --legacy-peer-deps, --force, npm overrides, peerDependenciesMeta, React version conflicts, and debugging with npm ls.

• Fix: npm WARN deprecated — inflight, glob, rimraf, and Other Package Warnings

  npm WARN deprecated [email protected], [email protected], [email protected], @humanwhocodes — which warnings are safe to ignore, which need fixing, and exact steps to silence each one.

• Fix: Yarn error Integrity check failed / EINTEGRITY sha512

  How to fix Yarn integrity check failed and EINTEGRITY sha512 errors caused by corrupted cache, lock file mismatches, registry issues, and network problems.

• Fix: npm ERR! cb() never called

  Resolve npm's cb() never called error by clearing cache, fixing network issues, updating npm, and resolving corrupted package-lock.json files.

• Fix: Yarn Integrity Check Failed – Expected and Got Different Results

  How to fix the Yarn error 'integrity check failed' or 'Lockfile does not satisfy expected package' caused by corrupted cache, outdated lockfile, or version mismatches.

• Fix: npm audit Found Vulnerabilities – How to Fix and Manage Security Issues

  How to fix npm audit vulnerabilities including high and critical severity issues, dependency conflicts, and when to use npm audit fix --force safely.

• Fix: EACCES: permission denied, mkdir / open / unlink (Node.js)

  How to fix EACCES permission denied errors in Node.js for mkdir, open, unlink, and scandir operations, covering npm global installs, Docker, NVM, CI/CD, and filesystem permissions.

• Fix: npm ERR! code ELIFECYCLE (errno 1, Failed at script)

  How to fix npm ERR! code ELIFECYCLE, npm ERR! errno 1, and npm ERR! Failed at the script errors. Covers reading the real error, node_modules corruption, node-gyp failures, wrong Node version, memory issues, postinstall failures, Windows-specific fixes, and more.

• Fix: npm ERR! Missing script: "start"

  How to fix "npm ERR! Missing script" for start, dev, build, and test. Covers adding scripts to package.json, common framework configurations for React, Next.js, Vite, Angular, Express, and Nest.js.

• Fix: npm ERR! ERESOLVE unable to resolve dependency tree

  How to fix the ERESOLVE unable to resolve dependency tree error in npm. Covers root causes, peer dependency conflicts, --legacy-peer-deps, --force, npm overrides, and edge cases with React 18, TypeScript, and monorepos.

• Fix: EACCES permission denied when installing npm packages globally

  How to fix 'Error: EACCES: permission denied, access /usr/local/lib/node_modules' when running npm install -g on macOS or Linux. Multiple solutions ranked by recommendation.

• Fix: Error Cannot find module in Node.js (MODULE_NOT_FOUND)

  How to fix 'Error: Cannot find module' and 'MODULE_NOT_FOUND' in Node.js. Covers missing packages, wrong import paths, node_modules issues, TypeScript moduleResolution, ESM vs CJS, and monorepo hoisting.

Bundlers & Build Tools (24)

• Fix: Bun Bundler Not Working — Targets, Format, Externals, Macros, and Code Splitting

  How to fix bun build errors — target (browser/bun/node) mismatch, format esm/cjs/iife, externals not respected, Bun macros at compile time, splitting and chunks, plugin API, and Bun.build vs CLI.

• Fix: Playwright Component Testing Not Working — Mount Fixture, Vite Config, Styles, and TypeScript

  How to fix Playwright component testing errors — playwright-ct.config not found, mount fixture undefined, CSS not loaded in tests, Vite alias for imports, TypeScript paths, hooks (beforeMount), and snapshot strategy.

• Fix: Sentry Source Maps Not Working — Release Matching, sentry-cli Upload, Vite/Webpack Plugins

  How to fix Sentry source maps errors — minified stack traces, release name mismatch between build and runtime, sentry-cli upload-sourcemaps options, Vite/Webpack/Next.js plugin setup, and hiding maps from public.

• Fix: React Compiler Not Working — ESLint Plugin, Babel Setup, Bail-Outs, and Vite/Next.js Config

  How to fix React Compiler issues — eslint-plugin-react-compiler not flagging, babel-plugin-react-compiler not running, 'Function contains a code construct that prevents compilation', Next.js 15 config, and removing useMemo/useCallback safely.

• Fix: React Router 7 Not Working — Framework Mode, Loaders, Type Safety, and Remix Migration

  How to fix React Router v7 errors — framework mode vs library mode setup, loader/action data type narrowing, route module exports missing, single-fetch revalidation, hydration mismatch, and Remix v2 migration paths.

• Fix: Tailwind v4 Not Working — @theme, CSS-First Config, PostCSS vs Vite, and v3 Migration

  How to fix Tailwind CSS v4 errors — tailwind.config.js ignored, @import 'tailwindcss' not loading, @theme custom values not applied, content scanning misses files, Vite plugin setup, and v3 to v4 migration gotchas.

• Fix: Vite Proxy Not Working — API Requests Not Forwarded or 404/502 Errors

  How to fix Vite dev server proxy issues — proxy configuration in vite.config.ts, path rewriting, WebSocket proxying, HTTPS targets, and common misconfigurations.

• Fix: Webpack Bundle Size Too Large — Reduce JavaScript Bundle for Faster Load Times

  How to reduce Webpack bundle size — code splitting, tree shaking, dynamic imports, bundle analysis, moment.js replacement, lodash optimization, and production build configuration.

• Fix: Webpack Dev Server Not Reloading — HMR and Live Reload Not Working

  How to fix Webpack dev server not reloading — Hot Module Replacement configuration, watchFiles settings, polling for Docker/WSL, HMR API for custom modules, and port conflicts.

• Fix: Webpack/Vite Path Alias Not Working — Module Not Found with @/ Prefix

  How to fix path alias errors in webpack and Vite — configuring resolve.alias, tsconfig paths, babel-plugin-module-resolver, Vite alias configuration, and Jest moduleNameMapper.

• Fix: Webpack Bundle Too Large — Chunk Size Warning

  How to reduce Webpack bundle size — code splitting, lazy loading, tree shaking, analyzing the bundle with webpack-bundle-analyzer, replacing heavy dependencies, and configuring splitChunks.

• Fix: Vite Environment Variables Not Working

  How to fix Vite environment variables showing as undefined — missing VITE_ prefix, wrong .env file for the mode, import.meta.env vs process.env, TypeScript types, and SSR differences.

• Fix: Vite Build Chunk Size Warning (Some Chunks Are Larger Than 500 kB)

  How to fix Vite's chunk size warning — why bundles exceed 500 kB, how to split code with dynamic imports and manualChunks, configure the chunk size limit, and optimize your Vite production build.

• Fix: React.lazy and Suspense Errors (Element Type Invalid, Loading Chunk Failed)

  How to fix React.lazy and Suspense errors — Element type is invalid, A React component suspended while rendering, Loading chunk failed, and lazy import mistakes with named vs default exports.

• Fix: TypeScript Path Aliases Not Working (Cannot Find Module '@/...')

  How to fix TypeScript path aliases not resolving — tsconfig paths configured but imports still fail at runtime, in Jest, or after building with webpack, Vite, or ts-node.

• Fix: Webpack HMR (Hot Module Replacement) Not Working

  How to fix Webpack Hot Module Replacement not updating the browser — HMR connection lost, full page reloads instead of hot updates, and HMR breaking in Docker or behind a proxy.

• Fix: Vite server connection lost / HMR not working

  How to fix the '[vite] server connection lost. Polling for restart...' error and HMR not working. Covers file watcher limits, WebSocket config, Docker polling, WSL2, proxy forwarding, SSL issues, firewall blocking, and dependency pre-bundling.

• Fix: Error: error:0308010C:digital envelope routines::unsupported

  How to fix the Node.js digital envelope routines unsupported error caused by OpenSSL 3.0 changes in Node.js 17+, with solutions for webpack, Vite, React, and Angular.

• Fix: Webpack Module Not Found – Can't Resolve '<module>' in '<directory>'

  How to fix the Webpack error 'Module not found: Error: Can't resolve' caused by missing packages, wrong paths, aliases, or extension resolution issues.

• Fix: Module parse failed: Unexpected token (Webpack / Vite / esbuild)

  How to fix 'Module parse failed: Unexpected token' in Webpack, Vite, and esbuild by configuring the correct loaders and transforms for JSX, TypeScript, CSS, JSON, and other file types.

• Fix: Loading chunk failed / ChunkLoadError

  How to fix 'Loading chunk failed', 'ChunkLoadError', and 'Failed to fetch dynamically imported module' in webpack, Next.js, React, and Vite. Covers stale deployments, CDN caching, publicPath misconfiguration, service worker cache, code splitting, dynamic import retry strategies, React.lazy error boundaries, and Next.js-specific solutions.

• Fix: ERR_CONNECTION_REFUSED (localhost refused to connect)

  How to fix 'ERR_CONNECTION_REFUSED', 'localhost refused to connect', and 'This site can't be reached' errors when accessing localhost in Chrome, Firefox, and Edge. Covers dev servers, port issues, 0.0.0.0 vs 127.0.0.1, Docker port mapping, WSL2, firewalls, and more.

• Fix: Module not found: Can't resolve / Cannot find module or its corresponding type declarations

  How to fix 'Module not found: Can't resolve' in webpack, Vite, and React, and 'Cannot find module or its corresponding type declarations' in TypeScript. Covers missing packages, wrong import paths, case sensitivity, path aliases, node_modules corruption, monorepo hoisting, barrel files, and asset imports.

• Fix: [vite] Internal server error: Failed to resolve import

  How to fix Vite's 'Failed to resolve import' error, including 'Does the file exist?', 'Optimized dependency needs to be force included', 'Pre-transform error', and '504 (Outdated Optimize Dep)'. Covers missing packages, path aliases, optimizeDeps, cache clearing, and CJS/monorepo edge cases.

More in this category (76)

• Fix: Passkey / WebAuthn Not Working — rpId, Origin, Conditional UI, and Cross-Device Sign-In

  How to fix passkey and WebAuthn errors — rpId mismatch, NotAllowedError, Conditional UI autofill not showing, attestation vs assertion, Safari userVerification quirks, and SimpleWebAuthn library integration.

• Fix: Kafka Consumer Not Receiving Messages, Connection Refused, and Rebalancing Errors

  How to fix Apache Kafka issues — consumer not receiving messages, auto.offset.reset, Docker advertised.listeners, max.poll.interval.ms rebalancing, MessageSizeTooLargeException, and KafkaJS errors.

• Fix: OpenAI API Not Working — RateLimitError, 401, 429, and Connection Issues

  How to fix OpenAI API errors — RateLimitError (429), AuthenticationError (401), APIConnectionError, context length exceeded, model not found, and SDK v0-to-v1 migration mistakes.

• Fix: Directus Not Working — API Returning 403, Items Not Appearing, or Flows Not Triggering

  How to fix Directus issues — permissions, access policies, collections, REST and GraphQL APIs, file uploads, Flows automation, and self-hosted deployment.

• Fix: Sanity Not Working — GROQ Queries Returning Nothing, CORS Errors, or Studio Not Loading

  How to fix Sanity CMS issues — GROQ queries, CORS configuration, dataset permissions, image URLs, Portable Text, webhooks, and Next.js integration.

• Fix: AutoAnimate Not Working — Transitions Not Playing, List Items Not Animating, or React State Changes Ignored

  How to fix @formkit/auto-animate issues — parent ref setup, React useAutoAnimate hook, Vue directive, animation customization, disabling for specific elements, and framework integration.

• Fix: Blurhash Not Working — Placeholder Not Rendering, Encoding Failing, or Colors Wrong

  How to fix Blurhash image placeholder issues — encoding with Sharp, decoding in React, canvas rendering, Next.js image placeholders, CSS blur fallback, and performance optimization.

• Fix: Docusaurus Not Working — Build Failing, Sidebar Not Showing, or Plugin Errors

  How to fix Docusaurus issues — docs and blog configuration, sidebar generation, custom theme components, plugin setup, MDX compatibility, search integration, and deployment.

• Fix: Embla Carousel Not Working — Slides Not Scrolling, Autoplay Not Starting, or Thumbnails Not Syncing

  How to fix Embla Carousel issues — React setup, slide sizing, autoplay and navigation plugins, loop mode, thumbnail carousels, responsive breakpoints, and vertical scrolling.

• Fix: Lottie Not Working — Animation Not Playing, File Not Loading, or React Component Blank

  How to fix Lottie animation issues — lottie-react and lottie-web setup, JSON animation loading, playback control, interactivity, lazy loading, and performance optimization.

• Fix: Prism React Renderer Not Working — No Syntax Colors, Wrong Language, or Custom Theme Not Applying

  How to fix prism-react-renderer issues — Highlight component setup, language support, custom themes, line highlighting, copy button, and integration with MDX and documentation sites.

• Fix: View Transitions API Not Working — No Animation Between Pages, Cross-Document Transitions Failing, or Fallback Missing

  How to fix View Transitions API issues — same-document transitions, cross-document MPA transitions, view-transition-name CSS, Next.js and Astro integration, custom animations, and browser support.

• Fix: dnd-kit Not Working — Drag Not Starting, Sort Order Not Updating, or Items Jumping on Drop

  How to fix dnd-kit issues — DndContext setup, sensors configuration, useSortable with SortableContext, drag overlays, collision detection algorithms, and accessible drag and drop.

• Fix: Expo Not Working — Build Failing, Native Module Not Found, or EAS Build Error

  How to fix Expo issues — Expo Go vs development builds, native module installation with expo-modules-core, EAS Build configuration, bare workflow setup, and common SDK upgrade problems.

• Fix: Framer Motion Not Working — Animation Not Playing, Exit Animation Skipped, or Layout Shift on Mount

  How to fix Framer Motion issues — variants, AnimatePresence for exit animations, layout animations, useMotionValue, server component errors, and performance optimization.

• Fix: Git Hooks Not Running — Husky Not Working, pre-commit Skipped, or lint-staged Failing

  How to fix Git hooks not executing — Husky v9 setup, hook file permissions, lint-staged configuration, pre-commit Python tool, lefthook, and bypassing hooks in CI.

• Fix: HTMX Not Working — hx-get Request Not Firing, Swap Not Updating DOM, or Response Ignored

  How to fix HTMX issues — attribute syntax, target and swap strategies, out-of-band swaps, event handling, CSP configuration, response headers, and debugging HTMX requests.

• Fix: Jotai Not Working — Atom Not Updating, Derived Atom Out of Sync, or atomWithStorage Hydration Error

  How to fix Jotai state management issues — atom scope, derived atoms, async atoms with Suspense, atomWithStorage SSR, useAtomValue vs useSetAtom, and debugging stale state.

• Fix: Nuxt Not Working — useFetch Returns Undefined, Server Route 404, or Hydration Mismatch

  How to fix Nuxt 3 issues — useFetch vs $fetch, server routes in server/api, composable SSR rules, useAsyncData, hydration errors, and Nitro configuration problems.

• Fix: React Native Reanimated Not Working — Worklet Error, useAnimatedStyle Not Updating, or Gesture Not Responding

  How to fix React Native Reanimated issues — worklet rules, shared values, useAnimatedStyle, Gesture Handler setup, web support, Babel plugin configuration, and Reanimated 3 migration.

• Fix: Remix Not Working — Loader Returns Undefined, Action Not Triggered, or Nested Route Data Missing

  How to fix Remix issues — loader and action setup, nested route outlet, useLoaderData typing, error boundaries, defer with Await, and common React Router v7 migration problems.

• Fix: shadcn/ui Not Working — Components Not Rendering, Styles Missing, or Dark Mode Broken

  How to fix shadcn/ui issues — Tailwind CSS v4 vs v3 configuration, CSS variables, dark mode setup, component installation, cn() utility, and common errors after adding components.

• Fix: Storybook Not Working — Addon Conflicts, Component Not Rendering, or Build Fails After Upgrade

  How to fix Storybook issues — CSF3 story format, addon configuration, webpack vs Vite builder, decorator setup, args not updating component, and Storybook 8 migration problems.

• Fix: styled-components Not Working — Styles Not Applying, SSR Flash of Unstyled Content, or Theme Not Available

  How to fix styled-components issues — ThemeProvider setup, Next.js SSR with ServerStyleSheet, shouldForwardProp, attrs, TypeScript theme typing, and styled-components v6 migration.

• Fix: SvelteKit Not Working — load Function Errors, Form Actions Failing, or SSR Data Not Available

  How to fix SvelteKit issues — load function data flow, +page.server.ts vs +page.ts, form actions with use:enhance, hooks.server.ts, SSR vs CSR mode, and common routing mistakes.

• Fix: TanStack Query Not Working — Data Not Fetching, Cache Not Updating, or Mutation Not Triggering Re-render

  How to fix TanStack Query (React Query v5) issues — query keys, stale time, enabled flag, mutation callbacks, optimistic updates, QueryClient setup, and SSR with prefetchQuery.

• Fix: TanStack Table Not Working — Sorting Not Triggering, Filters Ignored, or Pagination Showing Wrong Data

  How to fix TanStack Table (React Table v8) issues — column definitions, server-side sorting and filtering, row selection, virtual rows with TanStack Virtual, and v7 to v8 migration errors.

• Fix: Tauri Not Working — Command Not Found, IPC Error, File System Permission Denied, or Build Fails

  How to fix Tauri app issues — Rust command registration, invoke IPC, tauri.conf.json permissions, fs scope, window management, and common build errors on Windows/macOS/Linux.

• Fix: Turborepo Not Working — Cache Never Hits, Pipeline Not Running, or Workspace Task Fails

  How to fix Turborepo issues — turbo.json pipeline configuration, cache keys, remote caching setup, workspace filtering, and common monorepo task ordering mistakes.

• Fix: Valtio Not Working — Component Not Re-rendering, Snapshot Stale, or Proxy Mutation Not Tracked

  How to fix Valtio state management issues — proxy vs snapshot, useSnapshot for React, subscribe for side effects, derived state with computed, async actions, and Valtio with React Server Components.

• Fix: WebAssembly (WASM) Not Working — Module Fails to Load, Memory Error, or JS Interop Broken

  How to fix WebAssembly issues — instantiateStreaming vs instantiate, CORS for WASM files, linear memory limits, wasm-bindgen JS interop, imports/exports mismatch, and WASM in bundlers.

• Fix: Zustand Not Working — Component Not Re-rendering, State Reset on Refresh, or Selector Causing Infinite Loop

  How to fix Zustand state management issues — selector optimization, persist middleware, shallow comparison, devtools setup, slice pattern for large stores, and common subscription mistakes.

• Fix: Express Middleware Not Working — Order Wrong, Errors Not Caught, or async Errors Silently Dropped

  How to fix Express middleware issues — middleware execution order, error-handling middleware signature, async error propagation with next(err), and common middleware misconfigurations.

• Fix: IndexedDB Not Working — Transaction Inactive, Upgrade Blocked, or Store Not Found

  How to fix IndexedDB issues — transaction lifecycle, version upgrades, blocked events, cursor iteration, IDBKeyRange queries, and using idb wrapper library to avoid callback hell.

• Fix: React useTransition Not Working — UI Still Freezes, isPending Never True, or Transition Not Deferred

  How to fix React useTransition and startTransition issues — what counts as a transition, Suspense integration, concurrent rendering requirements, and common mistakes that prevent transitions from deferring.

• Fix: Vue Router Params Not Updating — Component Not Re-rendering or beforeRouteUpdate Not Firing

  How to fix Vue Router params not updating when navigating between same-route paths — watch $route, beforeRouteUpdate, onBeforeRouteUpdate, and component reuse behavior explained.

• Fix: Web Worker Not Working — postMessage Ignored, Cannot Import Module, or Worker Crashes Silently

  How to fix Web Worker issues — postMessage data cloning, module workers, error handling, SharedArrayBuffer setup, Comlink, and common reasons workers silently fail.

• Fix: Vue Teleport Not Rendering — Content Not Appearing at Target Element

  How to fix Vue Teleport not working — target element not found, SSR with Teleport, disabled prop, multiple Teleports to the same target, and timing issues.

• Fix: React Portal Event Bubbling Not Working — Events Not Reaching Parent

  How to fix React Portal event bubbling — understanding Portal event propagation, modal close on outside click, stopPropagation side effects, focus management, and accessibility.

• Fix: React StrictMode Double Render — Side Effects Running Twice in Development

  How to fix React StrictMode double render issues — understanding intentional double invocation, fixing side effects, useEffect cleanup, external subscriptions, and production behavior.

• Fix: Svelte Store Subscription Leak — Memory Leak from Unsubscribed Stores

  How to fix Svelte store subscription memory leaks — auto-subscription with $, manual unsubscribe, derived store cleanup, custom store lifecycle, and SvelteKit SSR store handling.

• Fix: Vue Composable Not Reactive — ref and reactive Losing Reactivity After Destructuring

  How to fix Vue composable reactivity loss — toRefs for destructuring, returning refs vs raw values, reactive object pitfalls, stale closures, and composable design patterns.

• Fix: Vue Composition API Reactivity Lost — Destructured Props or Reactive Object Not Updating

  How to fix Vue Composition API reactivity loss — destructuring reactive objects, toRefs, storeToRefs, ref vs reactive, watch vs watchEffect, and template not updating.

• Fix: React Native Android Build Failed

  How to fix React Native Android build failures — SDK version mismatches, Gradle errors, duplicate module issues, Metro bundler problems, and NDK configuration for common build errors.

• Fix: Flask CORS Not Working

  How to fix CORS errors in Flask — installing flask-cors correctly, handling preflight OPTIONS requests, configuring origins with credentials, route-specific CORS, and debugging missing headers.

• Fix: CSS Custom Properties (Variables) Not Working or Not Updating

  How to fix CSS custom properties not applying — wrong scope, missing fallback values, JavaScript not setting variables on the right element, and how CSS variables interact with media queries and Shadow DOM.

• Fix: GraphQL 400 Bad Request Error (Query Syntax and Variable Errors)

  How to fix GraphQL 400 Bad Request errors — malformed query syntax, variable type mismatches, missing required fields, schema validation failures, and how to debug GraphQL errors from Apollo and fetch.

• Fix: React Query (TanStack Query) Infinite Refetching Loop

  How to fix React Query refetching infinitely — why useQuery keeps fetching, how object and array dependencies cause loops, how to stabilize queryKey, and configure refetch behavior correctly.

• Fix: React Native Metro Bundler Failed to Start or Bundle

  How to fix React Native Metro bundler errors — unable to resolve module, EMFILE too many open files, port already in use, transform cache errors, and Metro failing to start on iOS or Android.

• Fix: Vue 3 Reactive Data Not Updating (ref/reactive Not Triggering Re-render)

  How to fix Vue 3 reactive data not updating the UI — why ref and reactive lose reactivity, how to correctly mutate reactive state, and common pitfalls with destructuring and nested objects.

• Fix: JavaScript Closure in Loop — All Callbacks Get the Same Value

  How to fix the JavaScript closure loop bug where all event handlers or setTimeout callbacks return the same value — using let, IIFE, bind, or forEach instead of var in loops.

• Fix: React.memo Not Preventing Re-renders

  How to fix React.memo not working — components still re-rendering despite being wrapped in memo, caused by new object/function references, missing useCallback, and incorrect comparison functions.

• Fix: Next.js Environment Variables Returning undefined

  How to fix Next.js environment variables returning undefined — NEXT_PUBLIC prefix rules, server vs client context, .env file loading order, and runtime vs build-time variable access.

• Fix: React Context Not Updating / Re-rendering Components

  How to fix React Context not triggering re-renders — caused by mutating state directly, wrong provider placement, stale closures, and missing value changes that React can detect.

• Fix: No Routes Matched Location in React Router v6

  How to fix 'No routes matched location' in React Router v6 — caused by missing Routes wrapper, wrong path syntax, nested route mismatches, and v5 to v6 migration issues.

• Fix: Electron 'require' Is Not Defined Error

  Fix the Electron 'require is not defined' error caused by contextIsolation, nodeIntegration changes, and learn to use preload scripts and contextBridge.

• Fix: Firebase Permission Denied Error

  How to fix the Firebase 'permission denied' or 'Missing or insufficient permissions' error in Firestore and Realtime Database. Covers security rules, authentication state, custom claims, Admin SDK, rule simulators, time-based rules, and document-level permissions.

• Fix: Jest Cannot Find Module Error

  How to fix the Jest 'Cannot find module' error by configuring moduleNameMapper, moduleDirectories, tsconfig paths, and resolving ESM, monorepo, and dependency issues.

• Fix: React Warning: Failed prop type

  How to fix the React 'Warning: Failed prop type' error. Covers wrong prop types, missing required props, children type issues, shape and oneOf PropTypes, migrating to TypeScript, default props, and third-party component mismatches.

• Fix: Next.js API route 404 Not Found or not responding

  How to fix Next.js API route 404 not found errors caused by wrong file paths, App Router vs Pages Router confusion, incorrect exports, and deployment issues.

• Fix: Next.js Module not found: Can't resolve 'fs' (or 'path', 'crypto', 'net')

  How to fix Next.js Module not found Can't resolve fs error caused by importing Node.js modules in client components, wrong server/client boundaries, and missing polyfills.

• Fix: React TypeError: Cannot read property 'map' of undefined

  How to fix React TypeError Cannot read property map of undefined caused by uninitialized state, async data loading, wrong API response structure, and missing default values.

• Fix: React Cannot update a component while rendering a different component

  How to fix React Cannot update a component while rendering a different component caused by setState during render, context updates in render, and Redux dispatch in render.

• Fix: React Warning: Each child in a list should have a unique "key" prop

  How to fix the React unique key prop warning caused by missing keys in lists, duplicate keys, index keys, nested maps, and dynamic list rendering issues.

• Fix: Invalid hook call. Hooks can only be called inside of the body of a function component

  How to fix the React Invalid hook call error caused by mismatched React versions, duplicate React copies, calling hooks outside components, and class component usage.

• Fix: Objects are not valid as a React child (found: [object Object])

  How to fix the React error 'Objects are not valid as a React child' caused by rendering plain objects, Date objects, Promises, or API responses directly in JSX.

• Fix: React Hook useEffect has a missing dependency warning

  How to fix the React Hook useEffect has a missing dependency warning — covers the exhaustive-deps rule, useCallback, useMemo, refs, proper fetch patterns, and when to safely suppress the lint warning.

• Fix: React useState not updating (state not changing after setState)

  How to fix React useState not updating. Covers async state updates, functional updates, object mutations, stale closures, setTimeout issues, React 18 batching, props initialization, and debugging state changes.

• Fix: Next.js Image Optimization Errors – Invalid src, Missing Loader, or Unoptimized

  How to fix Next.js Image component errors including 'Invalid src prop', 'hostname not configured', missing loader, and optimization failures in production.

• Fix: React Can't Perform a State Update on an Unmounted Component

  How to fix the React warning 'Can't perform a React state update on an unmounted component' caused by async operations, subscriptions, or timers.

• Fix: VSCode ESLint Extension Not Working – No Errors Shown or Not Running

  How to fix VSCode's ESLint extension when it stops highlighting errors, shows no output, or fails to start. Covers flat config, settings, and common misconfigurations.

• Fix: React useEffect runs infinitely (infinite loop / maximum update depth exceeded)

  How to fix useEffect infinite loops in React — covers missing dependency arrays, referential equality, useCallback, unconditional setState, data fetching cleanup, event listeners, useRef, previous value comparison, and the exhaustive-deps lint rule.

• Fix: CORS preflight request blocked — Response to preflight does not have HTTP ok status

  How to fix 'Response to preflight request doesn't pass access control check' and 'preflight channel did not succeed' CORS errors by handling OPTIONS requests, setting correct headers, and configuring your server.

• Fix: Hydration failed because the initial UI does not match what was rendered on the server (Next.js)

  How to fix the Next.js hydration mismatch error. Covers invalid HTML nesting, browser extensions, Date/time differences, useEffect for client-only code, dynamic imports, suppressHydrationWarning, localStorage, third-party scripts, Math.random, auth state, and React portals.

• Fix: Too many re-renders. React limits the number of renders to prevent an infinite loop.

  How to fix 'Too many re-renders' in React. Covers calling functions in JSX instead of passing references, setState in the render body, useEffect infinite loops, object/array dependency issues, and how to debug re-renders with React DevTools.

• Fix: React Hook "useXxx" is called conditionally. React Hooks must be called in the exact same order in every component render.

  How to fix 'React Hook is called conditionally', 'Rendered more hooks than during the previous render', 'Invalid hook call', and other React Hooks order errors. Covers conditional hooks, hooks in loops, hooks after early returns, duplicate React versions, and ESLint setup.