Flow on_crashed hook does not run

[julianhess]

Bug summary

The on_crashed hook does not execute, even though Prefect is clearly transitioning to a Crashed state. For instance, when a flow is sent a SIGINT via ^C, Prefect correctly traps the interrupt signal and transitions to a Crashed state but then does not execute the hook:

import prefect
from time import sleep

def crash_hook(*args):
    print("crashed!!!")

@prefect.flow(name = "test", on_crashed = [crash_hook])
def flow():
    sleep(10)

>>> flow()
21:07:07.610 | INFO    | prefect.engine - Created flow run 'spiritual-llama' for flow 'test'
21:07:07.612 | INFO    | prefect.engine - View at http://127.0.0.1:4200/runs/flow-run/2d5a7b50-5eb5-4f80-a98b-867b84908c4c
^C21:07:11.196 | ERROR   | Flow run 'spiritual-llama' - Crash detected! Execution was aborted by an interrupt signal.
21:07:11.235 | ERROR   | Flow run 'spiritual-llama' - Finished in state Crashed('Execution was aborted by an interrupt signal.')
---------------------------------------------------------------------------
KeyboardInterrupt                         Traceback (most recent call last)
...
<standard stack trace>
...

As you can see, crash_hook does not execute at all.

Note that the hook also fails to execute for other sorts of crash (not just SIGINT), e.g.

@prefect.flow(name = "test", on_crashed = [crash_hook])
def flow():
    raise SystemExit("crash!")

>>> flow()
21:18:39.626 | INFO    | prefect.engine - Created flow run 'amigurumi-chinchilla' for flow 'test'
21:18:39.627 | INFO    | prefect.engine - View at http://127.0.0.1:4200/runs/flow-run/73be1fc7-344b-4293-abe2-86c20c62e815
21:18:39.671 | ERROR   | Flow run 'amigurumi-chinchilla' - Crash detected! Execution was aborted by Python system exit call.
21:18:39.697 | ERROR   | Flow run 'amigurumi-chinchilla' - Finished in state Crashed('Execution was aborted by Python system exit call.')
An exception has occurred, use %tb to see the full traceback.

SystemExit: crash!

Again, the crash is properly intercepted, but the hook does not fire.

Version info

Version:             3.1.5
API version:         0.8.4
Python version:      3.12.7
Git commit:          3c06654e
Built:               Mon, Dec 2, 2024 6:57 PM
OS/Arch:             linux/x86_64
Profile:             local
Server type:         server
Pydantic version:    2.10.3

Additional context

No response

[zzstoatzz]

thank you for the report and the MRE @julianhess - we'll take a look at this!

[williamjamir]

@zzstoatzz Perhaps this task at #16436 can help clarify the issue as well.