celery with mongodb backend error -

after upgraded latest version of mongodb, celery task launch failed:

celery worker --beat --app=my.celerytask.task1:worker -g <config-files> --logfile <log-file>  --pidfile <pid-file> 

and getting following error:

[2015 - 07 - 13 11: 16: 10, 029: error / beat] beat: connection error: command son([('create', u 'messages.broadcast'), ('capped', true),  ('size', 100000.0)]) failed: collection exists.trying again in 32.0 seconds...  [2015 - 07 - 13 11: 16: 42, 190: error / mainprocess] consumer: cannot connect mongodb:    //x.x.x.x:27017 vo-db: command son([('create', u'messages.broadcast'),  ('capped', true), ('size', 100000.0)]) failed: collection exists.