Admob Interstitial ad showing Error building request URL

Issue

I have implemented admob interstitial ad recently and getting exception/error as Error building request URL. from method onAdFailedToLoad(), and also my ad is not shown .

My code:

InterstitialAd interstitialAd;
        protected void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);
        
                InterstitialAd interstitialAd = new InterstitialAd(MainActivity.this);
                interstitialAd.setAdUnitId(KEY);
                MobileAds.initialize(MainActivity.this, new OnInitializationCompleteListener() {
                    @Override
                    public void onInitializationComplete(InitializationStatus initializationStatus) {
                        Log.e("app","MobileAds onInitializationComplete");
                    }
                });
                interstitialAd.loadAd(new AdRequest.Builder().build());
                interstitialAd.setAdListener(new AdListener(){
                    @Override
                    public void onAdLoaded() {
                        Log.e("app","ad loaded");
                    }
        
                    @Override
                    public void onAdFailedToLoad(LoadAdError loadAdError) {
                        Log.e("app","ad failedToLoad: "+loadAdError.getMessage()); //error/exception here
                    }
                });
}
                  protected void onActivityResult(int requestCode, int resultCode, Intent data) {

        super.onActivityResult(requestCode, resultCode, data);
        if(interstitialAd.isLoaded()) {
                    interstitialAd.show();
                    Log.e("app","ad loaded");
                }
                else Log.e("app","ad not loaded yet");              
    }
}

I have registered my id properly in the Manifest.xml

<application>
<meta-data
            android:name="com.google.android.gms.ads.APPLICATION_ID"
            android:value="@string/KEY"/>
    </application>

Followed same guideline shown in here

Solution

Make sure you use the correct test ad ID from AdMob in the call InterstitialAd. This is not the same as your App ID, it has an attached slash and a number behind it.

For testing, use ca-app-pub-3940256099942544/1033173712 which is the test ID given by the docs at the time of writing.

Answered By - Uwe Post