FirebaseInstanceIdService is deprecated

[nigel12341]

'FirebaseInstanceIdService' is deprecated. Deprecated in Java

[amonkhepri]

Try updating gradle Firebase related implementations to current version

//firebase
implementation 'com.google.firebase:firebase-core:16.0.8'
implementation 'com.google.firebase:firebase-firestore:18.2.0'
implementation 'com.google.firebase:firebase-auth:16.2.1'
implementation 'com.firebaseui:firebase-ui-auth:4.3.1'
implementation 'com.google.firebase:firebase-storage:16.1.0'
implementation 'com.firebaseui:firebase-ui-storage:3.3.1'
implementation 'com.google.android.gms:play-services-auth:16.0.1'
implementation 'com.google.firebase:firebase-messaging:17.6.0'

[nocturnalbeast]

This is because FirebaseInstanceIdService has been replaced by FirebaseMessagingService.

You'll need to update your build.gradle files in the app folder to reflect the newer versions first, like @Amunratis has mentioned.

    implementation 'com.google.firebase:firebase-core:17.0.0'
    implementation 'com.google.firebase:firebase-firestore:20.1.0'
    implementation 'com.google.firebase:firebase-auth:18.0.0'
    implementation 'com.firebaseui:firebase-ui-auth:3.3.1'
    implementation 'com.google.firebase:firebase-storage:18.0.0'
    implementation 'com.firebaseui:firebase-ui-storage:3.3.1'
    implementation 'com.google.android.gms:play-services-auth:17.0.0'
    implementation 'com.google.firebase:firebase-messaging:19.0.1'

This is just similar to what he has mentioned, but the main modules you must upgrade are the core and the messaging modules.

After doing so, you'll need to modify the MyFirebaseInstanceIDService class by making it inherit the FirebaseMessagingService instead of the FirebaseInstanceIdService like so:

class MyFirebaseInstanceIDService : FirebaseMessagingService() {

Then replace the onTokenRefresh() function with the onNewToken() as given below:

    override fun onNewToken(token: String) {
        super.onNewToken(token)
        if (FirebaseAuth.getInstance().currentUser != null)
            addTokenToFirestore(token)
    }