注册任务时，KeyError 在 celery 上收到类型为“”的未注册任务

Question

I'm a bit new in celery configs.

I have a task named myapp.tasks.my_task for example.

I can see myapp.tasks.my_task in registered tasks of celery when I use celery inspect registered . doesn't it mean that the task is successfully registered? why it raises the following error for it:

KeyError celery.worker.consumer.consumer in on_task_received

Received unregistered task of type 'my_app.tasks.my_task'.
The message has been ignored and discarded.

Did you remember to import the module containing this task?
Or maybe you're using relative imports?

Please see
http://docs.celeryq.org/en/latest/internals/protocol.html
for more information.

The full contents of the message body was:
'[[], {}, {"callbacks": null, "errbacks": null, "chain": null, "chord": null}]' (77b)

there are also other tasks in my_app.tasks and they work correctly but only this task does not work and gets KeyError :

@shared_task(queue='celery')
def other_task():
   """ WORKS """
   ...

@shared_task(queue='celery')
def my_task():
   """ DOES NOT WORK """
   ...

Answer 1

It means that Celery can't find the implementation of the task my_app.tasks.my_task when it was called. Some possible solutions you may want to look at:

Possible Solution 1:

You probably haven't configured correctly either:

• Celery imports eg celery_app.conf.update(imports=['my_app.tasks']) or celery_app.conf.imports = ['my_app.tasks']
• Or Celery include ( example ) eg celery_app = Celery(..., include=['my_app.tasks'])

Note: If in a Django application, this can be skipped if already using celery_app.autodiscover_tasks() since the tasks are automatically discovered in the location ./<app_name>/tasks.py

Possible Solution 2:

If you are only importing my_app eg celery_app.conf.update(imports=['my_app']) then I assume you have a file my_app/__init__.py Make sure that inside that file, it imports the task my_app.tasks.my_task along with my_app.tasks.other_task so that the celery app knows that such task exists.

# Contents of my_app/__init__.py
from my_app.tasks import (
    my_task,
    other_task,
)

Possible Solution 3:

In case the my_task was just newly added (whereas other_task was already an old existing task), you might not have restarted the celery worker yet to see the new task. Try restarting the worker.

Answer 2

Another solution can be adding a name param in the shared_task decorator, ie,

@shared_task(queue='celery', name='other_task')
def other_task():
   """ WORKS """
   ...

@shared_task(queue='celery', name='my_task')
def my_task():
   """ DOES NOT WORK """
   ...

I see this in a full demo project https://github.com/melikesofta/django-dynamic-periodic-tasks , and the related code can be find here .

Answer 3

I could solve the error by just restarting Celery . I use Celery 5.1.2 :

celery -A core worker --pool=solo -l info