Flower: 'Unknown worker' error with celery==4.3.0

[volkerp]

Flower shows the list of workers and their states in the dashboard, but clicking on one results in an _Unknown worker ..._ error.

dependencies when the error occurs

amqp==2.5.0
billiard==3.6.0.0
celery==4.3.0
kombu==4.6.1
redis==3.2.1
vine==1.3.0

dependencies when working correctly

amqp==2.2.2
billiard==3.5.0.3
celery==4.2.1
kombu==4.2.0
redis==3.2.1
vine==1.1.4

Regards

[volkerp]

Futher digging into the dependencies shows that kombu is the culprit.
The error occurs when

kombu>=4.6.0

[Kub-AT]

The same here with kombu==4.6.1,
upgrade to 4.6.3 or downgrade to 4.2.1
helps to me

[rubimpassos]

Upgrading kombu to 4.6.3 solves this issue for me.
Thanks @Kub-AT

[yataosu]

Downgrading kombu to 4.2.1 solves this problem.
Thanks. @Kub-AT

[GoTop]

Suddently, I got this 'Unknown worker' error in Flower too.

and when I ran Flower in console, it said "inspect method failed":

[I 190627 13:20:38 mixins:224] Connected to redis://localhost:6379//
[W 190627 13:20:44 control:44] 'stats' inspect method failed
[W 190627 13:20:44 control:44] 'active_queues' inspect method failed
[W 190627 13:20:44 control:44] 'registered' inspect method failed
[W 190627 13:20:44 control:44] 'scheduled' inspect method failed
[W 190627 13:20:44 control:44] 'active' inspect method failed
[W 190627 13:20:44 control:44] 'reserved' inspect method failed
[W 190627 13:20:44 control:44] 'revoked' inspect method failed
[W 190627 13:20:44 control:44] 'conf' inspect method failed

and it is my package version:

kombu 4.2.1
redis 2.10.6
celery 4.2.1
flower 0.9.3

[stormlifter]

I get this when using the Dockerfile, freshly pulled and then started the dockerfile and got the exact same set of errors

[I 190716 01:18:43 command:139] Visit me at http://localhost:8888
[I 190716 01:18:43 command:144] Broker: redis://redis:6379/0
[I 190716 01:18:43 command:147] Registered tasks: 
    ['celery.accumulate',
     'celery.backend_cleanup',
     'celery.chain',
     'celery.chord',
     'celery.chord_unlock',
     'celery.chunks',
     'celery.group',
     'celery.map',
     'celery.starmap']
[I 190716 01:18:43 mixins:224] Connected to redis://redis:6379/0
[W 190716 01:18:43 state:113] Substantial drift from celery@c2b1bafaf529 may mean clocks are out of sync.  Current drift is
    14400 seconds.  [orig: 2019-07-16 01:18:43.905048 recv: 2019-07-15 21:18:43.904256]

[W 190716 01:18:46 control:44] 'stats' inspect method failed
[W 190716 01:18:46 control:44] 'active_queues' inspect method failed
[W 190716 01:18:46 control:44] 'registered' inspect method failed
[W 190716 01:18:46 control:44] 'scheduled' inspect method failed
[W 190716 01:18:46 control:44] 'active' inspect method failed
[W 190716 01:18:46 control:44] 'reserved' inspect method failed
[W 190716 01:18:46 control:44] 'revoked' inspect method failed
[W 190716 01:18:46 control:44] 'conf' inspect method failed

Edit: Seems to be related to docker, if I start a worker on the same container Flower can see both the one on that container and off, but only the on-container can be clicked on to see worker's details

[sknzl]

Getting same error here

[I 190820 13:20:38 mixins:229] Connected to 
 redis://localhost:6379//
[W 190820 13:20:41 control:44] 'stats' inspect method failed
[W 190820 13:20:41 control:44] 'active_queues' inspect method failed
[W 190820 13:20:41 control:44] 'registered' inspect method failed
[W 190820 13:20:41 control:44] 'scheduled' inspect method failed
[W 190820 13:20:41 control:44] 'active' inspect method failed
[W 190820 13:20:41 control:44] 'reserved' inspect method failed
[W 190820 13:20:41 control:44] 'revoked' inspect method failed
[W 190820 13:20:41 control:44] 'conf' inspect method failed

With following versions

kombu==4.6.4
redis==3.3.8
celery==4.3.0
flower==0.9.3

Any suggestions?

[xenozauros]

Got the same issue.
Using docker. Redis brocker

kombu==4.6.3
redis==3.3.7
celery==4.3.0
flower==0.9.3
vine==1.3.0

[adv27]

I got the same problem, downgrading the kombu from 4.6.4 => 4.6.3 solve it

[Kub-AT]

https://github.com/mher/flower/issues/924
kombu=4.6.4 Related kombu issue: https://github.com/celery/kombu/issues/1081

[elraro]

Hello,

how can i downgrade kombu? I don't find dependence

Thank you! Regards,

[cdknorow]

kombu 4.6.4 also seems to be breaking the app.control.inpsect() method for celery. It just doesn't find any workers at all. Downgrading fixes this.

[363568233]

flower 0.9.3
celery 4.3.0
kombu 4.6.5 also has this issue

[metalshanked]

The issue seems to be fixed in the latest version of kombu 4.6.6
pip install --upgrade kombu

[frost-nzcr4]

Latest celery==4.4.0rc4, kombu==4.6.6 & flower@master a7f8837a9691a8de376989830b03c2daacf537b7 works again

[Hammit]

amqp==2.5.2
billiard==3.6.1.0
celery==4.3.0
flower==0.9.3
kombu==4.6.7
redis==3.2.1
vine==1.3.0

Working for me

[smsajjadzaidi]

I am facing this same unknown celery worker error
I tried downgrading kombu to 4.2.0 and upgrading it to 4.6.11 as well
But these did not work out for me
Current stack:
celery = 4.4.0
kombu = 4.6.11
redis = 3.3.11
flower==0.9.5
amqp==2.6.1
vine==1.3.0
billiard==3.6.1.0