Firebase Push Notifications not received if app is closed
I'm testing Firebase Push notifications, sending a notification from the Firebase composer panel, and I noticed that if I close the app process from App Information panel, the push notifications sent doesn't reach the device. Even if I start again the app the notification is lost and is never received.
I also tryed this:
close the app process -> shut down the device -> power on the device -> send a notification... and the notification is not received!
It seems that firebase can only receive notifications if the device has the app started and not 100% closed, I mean, closing it just with back key but not killing the app process.
How is this possible? It is supossed that firebase should receive notifications even with the app closed.
I'm testing on a Nexus 5X with Android 8.0 and I'm using the last version of Firebase push Notifications.
Answer
Sorry for the late, but hope this help next users that will have this problem because there is no answer selected as "Solution".
When setup correctly the service, this will work even the app is closed. That because, Firebase Messages travel by Google Play Services so closing your app doesn't have a relation with the service.
At first, notification never came. By searching in the device settings I saw that the energy saving system for my app was active (when closed was removed from stack) so notification was sent but my app couldn't take and display these.
After disabling that option, I've test many time and I found that sometimes notification come with a late of 2-3 minutes when app is completely closed. Sometimes it touch the 5 minutes. You need to be patient and it will come!
Instead, When app is opened or closed simply by back button, notification come in few seconds.