# prefect-community

Chris Marchetti [Datateer]

11/23/2022, 6:31 PM
Hello Prefect community. We are getting an
Unknown Opcode
error in our prefect flow. I looked up the error and saw several issues relating to mismatched python versions. I have verified that we are using python 3.8 (3.87 and 3.8) for everything. Does anyone have any ideas why this error may be occurring? Other tasks in our flow ran successfully. Only one failed.

Mason Menges

11/23/2022, 8:54 PM
Hey @Chris Marchetti [Datateer] Do you have the full stack trace for the error or a minimum reproducible example of the flow that's running? Mismatched python versions are a common reason this could come up but it's hard to guess beyond that without more information 😅

Chris Marchetti [Datateer]

11/23/2022, 10:07 PM
I was able to rebuild the flow making sure that the python versions were identical 3.87 and it is sill throwing the error.
Copy code
Task 'build vars': Exception encountered during task execution!
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/prefect/engine/", line 876, in get_task_run_state
    value = prefect.utilities.executors.run_task_with_timeout(
  File "/usr/local/lib/python3.8/site-packages/prefect/utilities/", line 468, in run_task_with_timeout
    return*args, **kwargs)  # type: ignore
  File "/home/runner/work/pkt-pipeline/pkt-pipeline/orchestration/", line 24, in build_vars
SystemError: unknown opcode
The error is above.