GCM notifications suddenly stopped working , Not recieving notifications at all - google-cloud-messaging

Question

I have created an app with GCM notifications and moved it to live it was working well for quite some time, 2, 3 months then suddenly stopped receiving notifications. Gone the code but not able to understand what went wrong and where should I fix.
Here is my manifest.xml
<activity android:name="com.ind.MainActivity"/>
<activity android:name="com.ind.ChaptersActivity"/>
<activity android:name="com.ind.SectionsListActivity"/>
<activity android:name="com.ind.SectionDetailActivity"/>
<activity android:name="com.ind.RuleDetailsActivity"/>
<activity android:name="com.ind.PartsListActivity"/>
<activity android:name="com.ind.PartsDetailActivity"/>
<activity android:label="#string/title_activity_web_dev" android:name="com.ind.Circulars"/>
<activity android:name="com.ind.CircularsDetailsActivity"/>
<activity android:label="#string/title_activity_web_design" android:name="com.ind.Notifications"/>
<activity android:label="#string/title_activity_web_maintain" android:name="com.ind.PressNotes"/>
<activity android:name="com.ind.UpdateDetailsActivity"/>
<activity android:name="com.ind.NotificationDetailsActivity"/>
<activity android:name="com.ind.UpdatesActivity"/>
<activity android:name="com.ind.Comparision"/>
<activity android:name="com.ind.ComparisionActivity"/>
<receiver android:name="com.google.android.gcm.GCMBroadcastReceiver" android:permission="com.google.android.c2dm.permission.SEND">
<intent-filter>
<action android:name="com.google.android.c2dm.intent.RECEIVE"/>
<action android:name="com.google.android.c2dm.intent.REGISTRATION"/>
<category android:name="com.ind"/>
</intent-filter>
</receiver>
<service android:name=".GCMIntentService"/>
<meta-data android:name="com.google.android.gms.version" android:value="#integer/google_play_services_version"/>
</application>
Please let me know is there is something wrong.
From Database I could see that devices are registering properly, and all see the same thing from logs even.

Answer 1

You should be sure that you correctly proccesses these things:
NotRegistered is error code from GCM server. Getting this code you should immediately remove regId from your database
cannonical_ids is a signal that you should replace regId with new one
You must request new regId from GCM while updating your client app
Also if you have all regIds in your database, you can try to send test push to them and check what is respone from GCM. You can use my dev push server for these purposes.