Sending Push Notification using GCM registration token throws Not_Registered error on Android App

[Mayank Bhatnagar]

Hi, 

We have recently come across an issue with push messages not being received at our Moble app User's end. The issue comes while sending the Push Messages from server as Not_Registered, even though the device was successfully registered on the GCM server and was getting push messages earlier. We also have a callback within the app for Token refresh in case the token would have expired, and then notify the new token to our sever. Not sure what could be causing this to happen and would request your support for the same. For your reference, I am sharing some GCM tokens for which we are getting this error 

1. c2GC-x9Vhj0:APA91bEX1MKAK1Cmbyjk8qser0tycJo44nGwT2Itd3Gj8JB1K31a5mOE-eD9BVVVoU_voO8i3SbrXLNV5JPKuQL58Pnkzt2beqD4VyQf-iWVcwz5J8OmPY5BQEjy5H7QJb2qZ1Ag9CmH
   
2. cfANXBX-b8Y:APA91bG9frIUkQcR_NBiSXdnKcFlN-5PboVGVQfUMrOwPf_4W_1U3vHL4E55GnnZEduHICUZyTul7QLJg55Fql8o9znOp8-FteZqkb9VzoeglopJku21583BqqWWevchFXbuxINFphI6
   
3. c_LprdL7ChQ:APA91bEUnn-B8JIgIKfC9HX5o0LTsrnzOLWLamU8b-7Z3gRJGI3sptyjEG-bhnTZcZLE46zSrI-h5ENm2_5xDtY7m2tzGYkKtveB2_6QF2iFZC0NHuqQXIzsM3c0ZFgjv-xNhsH6EaPA
   
4. c0jXZ_SZvc0:APA91bEd7Yyyoqwf_lLgSf-cVY_X4FyJScAB91YMqFbLR6NFDuJPF0PHuhdArdbuolOCT-8XgTnSmjk1a716lOu2Q70weu1HSrh-nNHSeJ5jWjvKLMNru-HZPQ2CaKPkeREdOSVNDcRK
   

Also I would like to know if there are any server side API to validate scenarios like: valid token, unregister token etc.

Mayank

[Jen Person]

So these are devices you have in your possession, and you can confirm that the devices did not uninstall that app? And when the token is refreshed, what is the process for ensuring you're replacing the previous token instead of storing an additional token? Without code, it's difficult to tell what's going on here. A good place to start would be the Instance ID server. You can find out more information on an instance ID from there.