When we try to send push notifications to android users using GCM, some users are not getting the push notification but when we troubleshoot the message id, it is showing Acknowledged from the Client app to GCM but not showing on their Notification Drawer.
Please help us to resolve this problem.
There are various reasons that this is happening. You might need to make sure that your GCM setup is configured properly as stated in this SO thread:
- Make sure you've set your SENDER ID you've received from Google correctly.
- Make sure your device was registered with Google's GCM service correctly.
- Make sure you are sending the push to the correct reg id you've received from Google. and that you didn't receive an error from Google GCM service.
- Have you set the delay_while_idle = 1? This means the message won't reach the device if it's idle (off, offline, locked screen, etc...).
- Change it to delay_while_idle = 0 if you want your wakelock permission to make any difference. Please read more here.
- Some times it takes time for the push to arrive (but never too much time, then there is a problem). Check what's the "time to live" of the push you've sent.
Also worth checking is this blog which tries to address the same question. Here are the outlined reasons:
- Notifications can be blocked by User at OS Level
- Device specific issues
- User Not connected to GCM due to Network issues
- Time to Live expires before notification delivery
- Gap from GCM in marking token as in-active
