AttributeError: 'Flask' object has no attribute 'user_options'
The Flask Celery Based Background Tasks page (http://flask.pocoo.org/docs/patterns/celery/) suggests this to start celery:
celery -A your_application worker
The your_application string has to point to your application’s package or module that creates the celery object.
Assuming the code resides in application.py, explicitly pointing to the celery object (not just the module name) avoided the error:
celery -A application.celery worker