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

<p>The stack trace is as follows:</p>

<pre><code>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)
</code></pre>

<p>This is version 9.6.1 and we're also using other Firebase components:</p>

<pre><code>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"
</code></pre>

<p>As I can see <a href="https://firebase.google.com/docs/remote-config/use-config-android" rel="noreferrer">from the documentation</a> and <a href="https://developers.google.com/android/reference/com/google/firebase/FirebaseApp" rel="noreferrer">the Javadoc</a> we shouldn't have to do any manual initialization in our case.</p>

<p>The exception happens on Android 4-6 on a variety of devices.</p>

<p><strong>Edit:</strong></p>

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