python

FastAPI background task execution error

RuntimeError: BackgroundTask.*after response

Fixes

1.Return BackgroundTasks in the route function parameter, not manually
2.Ensure background task function doesn't depend on request lifecycle
3.Use Celery or asyncio.create_task() for long-running tasks instead

fastapibackground-tasks

Related Errors

Asyncio event loop already running

RuntimeError: This event loop is already running

•Use nest_asyncio.apply() to allow nested event loops
•Use asyncio.run_coroutine_threadsafe() instead of asyncio.run()

Coroutine never awaited

RuntimeWarning: coroutine '.*' was never awaited

•Add 'await' before the coroutine call
•Use asyncio.create_task() to schedule the coroutine

Asyncio task was cancelled

asyncio\.CancelledError

•Handle CancelledError in try/except within the task
•Use asyncio.shield() to protect critical sections from cancellation