Hi, We are have a odd issue where after around 30 minutes of a flow running, the arguments passed to a task appear as NoneTypes. "`"AttributeError: 'NoneType' object has no attribute 'start_date'""` We running prefect server 0.15.6 with the KubernetesRun run config and DaskExecutor. I have verifyed that the time is the issue by implementing a delay in a upstream task - without the delay the flow run completes successfully.

Hey @Oliver Catterson, I think I need a bit more context here Is it a mapped task over Dask?

Yes it is a mapped task, All tasks after the 30 mins mark throw the NoneType error. I can provide some code if needed.

Do you have Dask worker logs? I think what is potentially happening is that the workers are dying or autoscaling down and the data is being lost. Not super sure though.

I'm also seeing this error now (a bit randomly)

Same question as above 😅. Are your workers dying somehow?

Not dask yet

Ah do you have a mapped task? It sounds like there is something failing silently in a task

A lot of mapped tasks

Is this specifically happening in one of those? Does the task upstream of that fail intermittently?