Attempt to invoke virtual method com.google.firebase.iid.FirebaseInstanceId.getInstanceId()' on a null object reference

Question

I am to using firebase-messaging library and trying to fetch the token using below method on app launch.

FirebaseInstanceId.getInstance().getInstance         


        

Answer 1

There was problem in merged manifest, following service was missing from the merged manifest. Added same to AndroidManifest.xml it worked like a charm.

 <service android:name="com.google.firebase.components.ComponentDiscoveryService" >
            <meta-data
                android:name="com.google.firebase.components:com.google.firebase.iid.Registrar"
                android:value="com.google.firebase.components.ComponentRegistrar" />
 </service>

Everything is working fine now.

Answer 2

You need add the below packages,

1. Xamarin.Firebase.Lid
2. Xamarin.Firebase.Messaging
3. Xamarin.Firebase.Common

Optional - Xamarin.Firebase.Analytics (For analytics)

Answer 3

I Face the same problem while merging .aar manifest with the main app manifest , As @alphaguy mention that there are missing Components after merging the manifest , And After add the following service as he mention the error is gone :

<service
        android:name="com.google.firebase.components.ComponentDiscoveryService"
        android:exported="false" >
        <meta-data
            android:name="com.google.firebase.components:com.google.firebase.iid.Registrar"
            android:value="com.google.firebase.components.ComponentRegistrar" />
        <meta-data
            android:name="com.google.firebase.components:com.google.firebase.messaging.FirebaseMessagingRegistrar"
            android:value="com.google.firebase.components.ComponentRegistrar" />
    </service>

But still firebase Messaging not work because WakefulBroadcastReceiver that receives FirebaseInstanceId and FirebaseMessaging events and delivers them to the application-specific FirebaseInstanceIdService is missing too , This receiver is automatically added to your application's manifest file via manifest merge , in our case it was missing in the merge so we need to add it manually as follow :

<receiver
        android:name="com.google.firebase.iid.FirebaseInstanceIdReceiver"
        android:exported="false"
        android:permission="com.google.android.c2dm.permission.SEND" >
        <intent-filter>
            <action android:name="com.google.android.c2dm.intent.RECEIVE" />
        </intent-filter>
    </receiver>

FirbaseInstanceIdReceiver Documentation : https://firebase.google.com/docs/reference/android/com/google/firebase/iid/FirebaseInstanceIdReceiver

• Note : that you may need to add FirebaseApp.initializeApp(this); at onCreate in your ApplicationClass .

  public class MyApplicationClass extends Application {
  
  @Override
  public void onCreate() {
      super.onCreate();
      FirebaseApp.initializeApp(this);
  }