"Unable to get provider com.google.firebase.provider.FirebaseInitProvider" Error path Android

I have also faced same problem with Firebase when run application below API 19(< 4.4.2) devices due to error of Multidex. Then below solution work for me:

In app module build.gradle

android {
   ...
   defaultConfig {
       multiDexEnabled true
       ...
   }
}

dependencies {
  // add dependency 
  compile 'com.android.support:multidex:1.0.1'
}

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

update name in AndroidManifest.xml

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:name=".MyApplication"
    android:theme="@style/AppTheme">

     // ...
</application>

Crate a MyApplication.java file

public class MyApplication extends Application {

    @Override
    protected void attachBaseContext(Context base) {
       super.attachBaseContext(base);
       MultiDex.install(this);
    }

}

In AndroidStudio try to do this:

1. ctrl+alt+s
2. Click on "Build, Execution, Deployment
3. disable "Instant Run"

This should work

Disabling instant run fixed the issue for me.

Android Studio -> Preferences -> Build, Execution, Deployment -> Instant Run

-Uncheck the box next to "Enable Instant Run..."

-Click OK