Over the last few months, we have been integrating Firebase Cloud Messaging into our project. The project uses the Firebase SDK, wrapped in a Cordova plug-in (cordova-plugin-firebase).
It is all working great, that is for Android at least. For iOS it is partially working. We received a few complaints from customers about them not receiving notifications, while all of the other iOS devices were correctly receiving messages.
After on-site device checking, we found out:
- The device successfully obtained a FCM-token.
- This FCM-token was subscribed to all the correct topics.
- This FCM-token had the latest app version.
- Both individual push-notifications (to the device), as well as topic notifications were not received
- Messages from the Firebase Cloud Console were not received either
- sometimes reinstalling the app worked
- Receiving over Cellar/WiFi did not change anything
- Permission was granted to receive push notifications
It is very hard to debug an issue like this, because installing a development version fixes it for some reason.
What are possible reasons for Firebase to not deliver the message to iOS? Or is it possible to see whether a delivery to APNS fails within the Firebase Console?