I have a flow that is passing pandas DataFrames between tasks. When it runs in Prefect Cloud, I get this logging error that I don't see locally:

April 22nd 2020 at 12:02:34pm EDT | CloudHandler
CRITICAL 
Failed to write log with error: Object of type ndarray is not JSON serializable

Hi @Luke Orland ! Prefect uses

cloudpickle

to serialize payloads between tasks - that error could be because the DataFrame isn't serializable. I'll also check on the logs side to be sure there's nothing happening in Cloud that could be causing that.

Dataframes are not usually serializable and the the individual data points themselves are normally of type

np.int64

or similar which are not serializable also. So you need to make sure both things are converted to serializable types.

makes sense. I am in fact logging the DataFrames. That was a mistake. Thanks all!