Final Flow State - Prefect

The final state of a flow is determined by its return value. The following rules apply:

If an exception is raised directly in the flow function, the flow run is marked as FAILED.
If a flow returns a manually created state, it is used as the state of the final flow run. This allows for manual determination of final state.
If a flow returns an iterable of states, the presence of any FAILED state will cause the run to be marked as FAILED.

In any other situation in which the flow returns without error, it will be marked as COMPLETED.

<Warning> If you manipulate states programmatically, you can create situations in which tasks within a flow can fail and not cause flow run failure. For example: ```python from prefect import flow, task

@task def add_one(x): return x + 1

@flow def my_flow(): # avoided raising an exception via return_state=True state = add_one("1", return_state=True) assert state.is_failed()

# the flow function returns successfully!
return


If `state` were returned from the flow function, the run would be marked as `FAILED`.

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