Azure Notification Service: The remote server returned an error: (401) Unauthorized. ExpiredToken: .TrackingId: -

i making use of azure notification service.

i log result of every push notification send azure.

i following result / response:

"the remote server returned error: (401) unauthorized. expiredtoken: .trackingid:f38f2e96-23b9-4c5b-880g-1358c5c15316_g4,timestamp:9/1/2016 9:48:14 pm"

i 2 - 10 in row in space of 1 second. , starts working again.

here log:

date    result 2016-09-01 22:07:02.81  enqueued 2016-09-01 22:07:02.67  enqueued 2016-09-01 22:05:34.03  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:9bf11f89-9c54-4213-8e42 2016-09-01 22:04:44.52  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:36fb0e8b-7d0f-4145-a125 2016-09-01 22:04:44.51  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:23c76f68-52ca-404a-ad31 2016-09-01 22:04:44.09  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:ceb11915-745a-4924-80cf 2016-09-01 22:04:44.09  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:75c61cba-fadc-4c05-8fe2 2016-09-01 22:03:52.82  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:e3696e3d-a44b-4179-a14a 2016-09-01 22:03:52.82  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:ea3c040b-e358-461b-a56f 2016-09-01 22:03:52.40  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:2eb9901d-e267-4053-a6a4 2016-09-01 22:03:52.40  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:163730b1-b7ef-43e8-adaf 2016-09-01 22:03:51.98  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:f28412c5-262f-4891-b991 2016-09-01 22:03:51.55  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:48b5dc83-ee3a-4d3f-b525 2016-09-01 22:03:51.55  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:a64ce0b1-dd6d-4972-8990 2016-09-01 22:03:51.13  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:b43bde8d-febb-4624-99c6 2016-09-01 22:03:51.13  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:17bd762d-0b4b-450c-bf09 2016-09-01 22:03:50.71  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:9abef735-bf42-4494-9721 2016-09-01 22:03:50.71  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:3f9b9c82-e37e-48c4-931e 2016-09-01 22:03:50.29  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:685a2286-6f0b-4fdf-9dd6 2016-09-01 22:03:50.28  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:3715eee2-b4b6-4ec4-9141 2016-09-01 22:03:49.87  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:91212080-719f-4b95-b9da 2016-09-01 22:03:49.86  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:bd1f5ae4-1a38-40d6-87ba 2016-09-01 22:03:48.01  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:47307851-cd9b-4632-94b6 2016-09-01 22:03:22.07  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:c8a21d16-de82-4fef-b2e 2016-09-01 22:03:22.07  remote server returned error: (401) unauthorized. expiredtoken: .trackingid:1fe9246d-19fc-4818-b8a8 2016-09-01 22:03:11.44  enqueued 2016-09-01 22:03:11.34  enqueued 

what error message mean?

[after thinking]

could threading issue? way implemented code there singleton instance of notificationhubclient each task gets , calls sendgcmnativenotificationasync().

this racing issue. workaround, create new notificationhubclient every task (notificationhubclient light weight object).