Default FirebaseApp is not initialized

We're seeing a few exceptions with the message Default FirebaseApp is not initialized in this process com.example.app. Make sure to call FirebaseApp.initializeApp(Context) first. in our Android app in which we just added Firebase Remote Config.

The stack trace is as follows:

Fatal Exception: java.lang.IllegalStateException: Default FirebaseApp is not initialized in this process com.example.app. Make sure to call FirebaseApp.initializeApp(Context) first.
       at com.google.firebase.FirebaseApp.getInstance(Unknown Source)
       at com.google.firebase.remoteconfig.FirebaseRemoteConfig.getInstance(Unknown Source)
       at com.example.app.fragments.SomeFragment.updateFooter(SourceFile:295)
       at com.example.app.fragments.SomeFragment.onCreateView(SourceFile:205)
       at android.support.v4.app.Fragment.performCreateView(SourceFile:2080)
       at android.support.v4.app.FragmentManagerImpl.moveToState(SourceFile:1108)
       at android.support.v4.app.FragmentManagerImpl.moveToState(SourceFile:1290)
       at android.support.v4.app.BackStackRecord.run(SourceFile:801)
       at android.support.v4.app.FragmentManagerImpl.execSingleAction(SourceFile:1638)
       at android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(SourceFile:679)
       at android.support.v4.app.FragmentPagerAdapter.finishUpdate(SourceFile:143)
       at android.support.v4.view.ViewPager.populate(SourceFile:1240)
       at android.support.v4.view.ViewPager.populate(SourceFile:1088)
       at android.support.v4.view.ViewPager.setAdapter(SourceFile:542)
       at com.example.app.SomeActivity.onSomeAsyncCallback(SourceFile:908)
       at com.example.app.SomeDataRetriever.onAsyncHttpCompleted(SourceFile:72)
       at com.example.app.io.AsyncHttp.onPostExecute(SourceFile:141)
       at com.example.app.io.AsyncHttp.onPostExecute(SourceFile:19)
       at android.os.AsyncTask.finish(AsyncTask.java:679)
       at android.os.AsyncTask.access$500(AsyncTask.java:180)
       at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:696)
       at android.os.Handler.dispatchMessage(Handler.java:102)
       at android.os.Looper.loop(Looper.java:150)
       at android.app.ActivityThread.main(ActivityThread.java:5665)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:799)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:689)

This is version 9.6.1 and we're also using other Firebase components:

compile 'com.google.firebase:firebase-ads:9.6.1'
compile 'com.google.firebase:firebase-config:9.6.1'
compile 'com.google.firebase:firebase-invites:9.6.1'
compile "com.google.firebase:firebase-messaging:9.6.1"

As I can see from the documentation and the Javadoc we shouldn't have to do any manual initialization in our case.

The exception happens on Android 4-6 on a variety of devices.

Edit:

I see this question gets a little bit of attention. I think this explanation can be interesting for some of you: https://firebase.googleblog.com/2016/12/how-does-firebase-initialize-on-android.html

Make sure to add to your root-level build.gradle

buildscript {
    // ...
    dependencies {
        // ...
        classpath 'com.google.gms:google-services:4.3.2'
    }
}

Then, in your module level Gradle file (usually the app/build.gradle), add the 'apply plugin' line at the bottom of the file to enable the Gradle plugin:

apply plugin: 'com.android.application'

android {
  // ...
}

dependencies {
  // ...
  implementation 'com.google.firebase:firebase-core:9.6.1'
  // Getting a "Could not find" error? Make sure you have
  // the latest Google Repository in the Android SDK manager
}

// ADD THIS AT THE BOTTOM
apply plugin: 'com.google.gms.google-services'

As said in documentation. I had exception as in a question above when forgot to add this in my gradle files.

I had this same issue some time ago.

You're trying to get an instance of Firebase without initialize it. Please add this line of code before you try to get an instance of Firebase, in your main function or a FutureBuilder:

FirebaseApp.initializeApp();

It seems that google-services:4.1.0 has an issue. Either downgrade it to

classpath 'com.google.gms:google-services:4.0.0'

or upgrade it to

classpath 'com.google.gms:google-services:4.2.0'

dependencies {
    classpath 'com.android.tools.build:gradle:3.3.0-alpha08'
    classpath 'com.google.gms:google-services:4.2.0'
    /*classpath 'com.google.gms:google-services:4.1.0' <-- this was the problem */
}

Hope it helps

I was missing the below line in my app/build.gradle file

apply plugin: 'com.google.gms.google-services'

and once clean project and run again. That fixed it for me.

UPDATE (11th Nov. 2021):

We do not need to call FirebaseApp.initializeApp(this); anywhere manually. and we should not too.

Possibility 1:

It seems that com.google.gms:google-services:4.3.9 has an issue.

We can either UPGRADE it to

classpath 'com.google.gms:google-services:4.3.10'

or DOWNGRADE it to

classpath 'com.google.gms:google-services:4.3.8'

dependencies {
    classpath 'com.android.tools.build:gradle:4.2.2'
    classpath 'com.google.gms:google-services:4.3.9'// <-- this was the problem
}

Possibility 2:

Make sure to add the below line in app/build.gradle file

apply plugin: 'com.google.gms.google-services'

then clean project and run again. It worked for me.

Possibility 3:

I just faced the same issue about it and got an unexpected and strange solution.

From this answer:

I have removed tools:node="replace" and it's working like charm.