Unable to get provider com.google.android.gms.ads.MobileAdsInitProvider: java.lang.IllegalStateException

This happened due to updated AdMob SDK. Now you need to add appID in your manifest file.

<application> . . . 
      <meta-data 
           android:name="com.google.android.gms.ads.APPLICATION_ID" 
           android:value="ca-app-pub-################~##########"/>
</application>

You can get appID from here -->Google addmob -->Select app --> App Settings --> App ID.

You can read more from here ads-developers.

If you want to use test ads before putting your own id check the AdMob test ids from here developers.google.

Hope this will help you. Thanks :)

Google gave update for the Google ads so if you update your Admob library in gradle then you need to add this in your manifest.

<manifest>
   <application>
      <!-- TODO: Replace with your real AdMob app ID -->
      <meta-data
          android:name="com.google.android.gms.ads.APPLICATION_ID"
          android:value="ca-app-pub-################~##########"/>
  </application>
</manifest>

Add In Your Manifest File

<meta-data
            android:name="com.google.android.gms.ads.AD_MANAGER_APP"
            android:value="true" />