Hi! I’m trying to run a flow locally with a prefect server. I have the server running as well as a local agent. When I run

flow.run()

, it errors out with this message:

TypeError: can't pickle _thread.lock objects

Note: I’m running the flow through a build system (bazel)

You are likely returning something that cant be pickled from a task like a connection. If you use DaskExecutor, Dask passes things to workers by pickling them

That’s weird. I’m not really passing or returning anything from any task. Does this include function calls within the task too?

No it does not. A good way to test is to do

cloudpickle.dumps()

on the output of the function