`is_serializable` returns False for "hello world" flow

Hi guys,

I have an issue on my flow that seems like it may be related to serialization.

So I’ve tried using the is_serializable function, which returned False for my flow. I have made my flow simpler to test it and kept getting False, until I tried the simple “Hello World” example from the homepage, and was surprised to see that that one too returns False for the flow:

from prefect import task, Flow
from prefect.utilities.debug import is_serializable

@task
def say_hello():
    print("Hello, world!")

with Flow("My First Flow") as flow:
    say_hello()

if is_serializable(flow) is False:
    raise ValueError('flow is not serializable at checkpoint 1')
    
flow.run() # "Hello, world!"

The output of the above is:

Traceback (most recent call last):
  File "hello.py", line 12, in <module>
    raise ValueError('flow is not serializable at checkpoint 1')
ValueError: flow is not serializable at checkpoint 1

Is this expected?

Thanks

[orcaman]

Thanks. I’m on MacOS Mojave 10.14.5 (18F132) with prefect-0.6.0 and Python 3.7.3

[jcrist]

Fixed by #2931. Closing.