Xamarin Android开发版AdMob加载失败（Failed to load ad:3）求助

Hey there! Let's dig into why your AdMob banners stopped loading with Failed to load ad: 3 after updating Visual Studio and your Google packages. First, let's clarify what that error code means:

Failed to load ad: 3 corresponds to ERROR_CODE_NO_FILL — this usually means the AdMob server doesn't have any ads to serve for your ad unit. But since your ads worked perfectly before the updates, it's highly likely the changes from updating VS and Google packages introduced a configuration issue that's preventing ads from loading properly (even if the error code says "no fill").

Could the updates be the cause? #

Absolutely. Here's why:

• Visual Studio updates: Often include updates to Xamarin.Android, which can change your project's target SDK version, build tools, or compatibility settings. AdMob has strict requirements for target SDK versions (e.g., current versions require targeting API 33+) and newer SDKs might enforce new permissions or privacy settings.
• Google package updates: Updating packages like Xamarin.GooglePlayServices.Ads can introduce breaking changes — new initialization methods, required manifest entries, or permission requirements that weren't needed in older versions.

Step-by-step troubleshooting #

Let's narrow down the issue with these checks:

1. Verify AdMob configuration in Manifest

   • Ensure you have the required APPLICATION_ID meta-data entry (newer AdMob versions mandate this):

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

   • Double-check that you have the necessary permissions:

     <uses-permission android:name="android.permission.INTERNET"/>
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
     

   • If your target SDK is API 33+, add the ad ID permission (required for ad targeting):

     <uses-permission android:name="com.google.android.gms.permission.AD_ID"/>
     

2. Test with AdMob's test ad units

   • Replace your ad unit ID with AdMob's official test IDs (e.g., for banners use ca-app-pub-3940256099942544/6300978111). If test ads load, the issue is likely a real "no fill" for your production ad unit (but since it worked before, this is less probable). If test ads also fail, you have a configuration problem tied to the updates.

3. Check your AdMob initialization code

   • Newer AdMob SDK versions require asynchronous initialization. Ensure you're using:

     MobileAds.Initialize(ApplicationContext, initializationStatus => {
         // Initialization complete
     });
     

   • Avoid old synchronous initialization patterns, as they might no longer work with updated packages.

4. Validate target SDK and Xamarin.Android versions

   • Go to your project's properties > Android Manifest, confirm the target SDK version matches what AdMob's current SDK supports. If VS auto-updated this to a higher version, you might need to adjust permissions or privacy settings accordingly.

5. Dig into detailed logs

   • Open LogCat in Visual Studio, filter for the Ads tag. Look for additional error messages (e.g., permission denials, initialization failures) that might explain why ads aren't loading — these logs will give you a clearer picture than just the generic error code 3.

Final thoughts #

The updates to Visual Studio and Google packages are almost certainly the trigger here, as they likely altered your project's environment or required configurations that your old setup didn't account for. Working through the steps above should help you identify and fix the issue quickly.

内容的提问来源于stack exchange，提问作者Badozvora