The support for this usage was removed in Celery 5.0. Instead you should use `-A` as a global option: celery -A celeryapp worker <...>
Solution 1:
As mentioned in the release notes (breaking changes) documentation:
The global options can no longer be positioned after the sub-command. Instead, they must be positioned as an option for the celery command
That means that you need to change from:
celery worker -A celeryapp <...>
to
celery -A celeryapp worker <...>