I tried to use Google Firebase Cloud Messaging to implement 'Push Notifications' function. Firstly, I registered in the firebase, and get the google-service file. Then I put the file in the resource of the application and set the config like the sample. The Andriod App has generated successfully, but when I installed it in the Andriod device to test it. I always got the error message "Couldn't register your device ".
This is probably because of what happened and how to solve it？Thanks.
Please ignore my first question, only now I noticed you shared the oap.
Are you sure you configured everything? The Google Services json file appears to be lacking something especially if you compare it with the one available on the Sample App.