TL;DR: Use set FORKED_BY_MULTIPROCESSING=1 on the worker script/shell

When running Celery on Windows 10, I got the following error:

ValueError: not enough values to unpack (expected 3, got 0)

This is quite unfortunate as Windows is supported on "best effort". A pull request has a change, but it's not pretty to patch an installation. To get around, you can just define an environment variable:

set FORKED_BY_MULTIPROCESSING=1

I only defined it on the worker's side.

HTH,