StackOverflow/23/01/FastAPI Starlette How to handle exceptions inside background tasks

• How to handle exceptions inside FastAPI/Starlette background tasks?

  • Question Summary

    • How to properly handle exceptions that occur in FastAPI/Starlette background tasks
    • What happens when an exception occurs in a background task
    • How to prevent unhandled exceptions from crashing the application

  • Key Points from Answer

    • Background tasks run after the response is sent, so exceptions cannot be sent back to the client
    • Global exception handlers (@app.exception_handler) don't catch background task exceptions
    • Best practice is to wrap task logic in try/except blocks:
      • python

        def background_job():
            try:
                # ... do work ...
            except Exception as e:
                logger.error(f"Background task failed: {e}")

    • Use proper logging instead of just print statements
    • Configure logging to flush before application exits
    • In development, ensure debugger is configured to catch exceptions in all threads

  • Related

    • FastAPI/Concept/Starlette BackgroundTasks with FastAPI and AsyncIO - Deep Research
    • FastAPI/Docs/Tutorial/Background Tasks
    • starlette/background/BackgroundTask