6 articles
RSSHow 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 Marshmallow errors — Schema not validated on dump, ValidationError messages format, unknown field handling, missing vs default, post_load object construction, and Marshmallow 3 to 4 migration.
How to fix Gunicorn errors — WORKER TIMEOUT killed, ImportError cannot import app, worker class not found, connection refused 502 behind nginx, graceful reload not working, and sync vs async worker selection.
How to fix Flask routes returning 404 — trailing slash redirect, Blueprint prefix issues, route not registered, debug mode, and common URL rule mistakes.
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.
How to fix Python's circular import error: ImportError cannot import name from partially initialized module. Covers lazy imports, module restructuring, TYPE_CHECKING, Django, Flask, and more.