Hello It might be a silly question but I can t really figure

Question

Hello It might be a silly question but I can t really figure out the answer One of the tasks of our flow is retried while it was previously already successful see screenshot And because this is a task calling a DELETE API endpoint the retried task failed because the object has already been removed Although I could easily handle such thing I would like to understand a bit more what s going on I suspect something failed somewhere in the flow and the flow is restarted from scratch and all the tasks are restarted I could not really find anything in the doc about that What would cause a flow to retry a task that has been previously successful Some precision prefect core 0 15 12 prefect server 2022 01 12

Kevin Kho · Answer

Are you on DaskExecutor

Kevin Kho · Answer

Dask has it s own retry mechanism in the event a worker crashes or something like that It will restart the worker and run the task graph again On Prefect Cloud we have a feature called Version Locking that will prevent the task from re running This is not in Server though

Romain · Answer

Yes I m using a DaskExecutor So it could be explained by a worker dying losing part of the task results and the flow being required to be rerun

Kevin Kho · Answer

Yes If Prefect submits A gt B gt C to Dask in one go and then A succeeds and B succeeds and then the worker dies it will restart and believe it needs to do A and B because they are upstream of C

Romain · Answer

Crystal clear Thanks