14 articles
RSSHow to fix Python aiosqlite errors — database is locked, WAL mode for concurrent reads, foreign_keys PRAGMA, row factory for dict-like rows, connection per request vs pool, datetime detect_types, and FastAPI integration.
How to fix APScheduler — BackgroundScheduler exits when script ends, jobs run multiple times under Gunicorn, AsyncIOScheduler not firing, misfire_grace_time skips, and timezone-aware cron triggers.
How to fix Python arq errors — worker can't find tasks, WorkerSettings class structure, cron syntax differences, msgpack serialization errors, job_id deduplication, result expiration, and Redis connection pooling.
How to fix msgspec errors — Struct field type not supported, ValidationError on decode, msgspec vs Pydantic differences, custom type hooks, frozen Struct mutation, and JSON Schema generation.
How to fix Tortoise ORM errors — Tortoise.init not called, no module imported model, fetch_related missing, aerich migration setup, FastAPI integration patterns, and ConfigurationError missing connection.
How to fix SQLModel errors — table not created without table=True, relationship not eager-loaded MissingGreenlet, AttributeError on lazy attribute, mixing Pydantic and Table classes, Optional vs default None, and async session setup.
How to fix Pydantic Settings errors — environment variables not picked up, .env file not loaded, ValidationError missing field, nested model env vars, SettingsConfigDict required, secret files, and BaseSettings import.
How to fix httpx errors — RuntimeError event loop is closed, ReadTimeout exception, ConnectionResetError, async client not closing properly, HTTP/2 not enabled, SSL verify failed, and proxy not working.
How to fix Uvicorn errors — Address already in use port binding, reload not detecting changes, SSL certificate errors, worker class with gunicorn, WebSocket disconnect, graceful shutdown, and proxy headers behind nginx.
How to fix FastAPI BackgroundTasks — task not executing, dependency injection in tasks, error handling, Celery for heavy tasks, and lifespan-managed background workers.
How to fix FastAPI dependency injection errors — async dependencies, database sessions, sub-dependencies, dependency overrides in tests, and common DI mistakes.
How to fix Python asyncio event loop blocking — using run_in_executor for sync calls, asyncio.to_thread, avoiding blocking I/O in coroutines, and detecting event loop stalls.
How to fix Pydantic ValidationError in Python — missing required fields, wrong types, custom validators, handling optional fields, v1 vs v2 API differences, and debugging complex nested models.
How to fix FastAPI 422 Unprocessable Entity error caused by wrong request body format, missing fields, type mismatches, query parameter errors, and Pydantic validation.