Now I have a two-page app with the first page to show an adMob banner.

When I move the app to the background, everything is good.

If I navigate to the second page, one logging message is shown.

E/Surface (12399): getSlotFromBufferLocked: unknown buffer: 0xbc288b10

Then I move the app to the background again, while in the second page, the app crashes with the following log.

E/BufferQueueProducer(12399): [ImageReader-1080x1794f1m3-12399-1](id:306f00000001,api:1,p:12399,c:12399) cancelBuffer: BufferQueue has been abandoned
D/AndroidRuntime(12399): Shutting down VM
E/AndroidRuntime(12399): FATAL EXCEPTION: main
E/AndroidRuntime(12399): Process: com.example.testapp, PID: 12399
E/AndroidRuntime(12399): java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.dispatchWindowVisibilityChanged(int)' on a null object reference
4
E/AndroidRuntime(12399):    at android.view.ViewGroup.dispatchWindowVisibilityChanged(ViewGroup.java:1614)
E/AndroidRuntime(12399):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2433)
E/AndroidRuntime(12399):    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1952)
E/AndroidRuntime(12399):    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:8171)
E/AndroidRuntime(12399):    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:972)
E/AndroidRuntime(12399):    at android.view.Choreographer.doCallbacks(Choreographer.java:796)
E/AndroidRuntime(12399):    at android.view.Choreographer.doFrame(Choreographer.java:731)
E/AndroidRuntime(12399):    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:957)
E/AndroidRuntime(12399):    at android.os.Handler.handleCallback(Handler.java:938)
E/AndroidRuntime(12399):    at android.os.Handler.dispatchMessage(Handler.java:99)
E/AndroidRuntime(12399):    at android.os.Looper.loop(Looper.java:223)
E/AndroidRuntime(12399):    at android.app.ActivityThread.main(ActivityThread.java:7656)
E/AndroidRuntime(12399):    at java.lang.reflect.Method.invoke(Native Method)
E/AndroidRuntime(12399):    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592)
E/AndroidRuntime(12399):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947)
I/Process (12399): Sending signal. PID: 12399 SIG: 9
Lost connection to device.

The first page source

import 'package:flutter/material.dart';
import 'package:google_mobile_ads/google_mobile_ads.dart';
import 'second_page_screen.dart';

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  MobileAds.instance.initialize();
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
          appBar: AppBar(
            title: const Text("Ads"),
          ),
          body: MainBody()),
    );
  }
}

class MainBody extends StatefulWidget {
  MainBody({Key? key}) : super(key: key);

  @override
  State<MainBody> createState() => _MainBodyState();
}

class _MainBodyState extends State<MainBody> {
  late BannerAd myBanner;
  late BannerAdListener listener;
  late AdWidget adWidget;
  late Container adContainer;

  @override
  void initState() {
    super.initState();

    listener = BannerAdListener(
      onAdLoaded: (Ad ad) => print('Ad loaded.'),
      onAdFailedToLoad: (Ad ad, LoadAdError error) {
        ad.dispose();
        print('Ad failed to load: $error');
      },
      onAdOpened: (Ad ad) => print('Ad opened.'),
      onAdClosed: (Ad ad) => print('Ad closed.'),
      onAdImpression: (Ad ad) => print('Ad impression.'),
    );

    myBanner = BannerAd(
      // final BannerAd myBanner = BannerAd(
      adUnitId: 'ca-app-pub-3940256099942544/6300978111',
      size: AdSize.largeBanner,
      request: const AdRequest(
        keywords: <String>['foo', 'bar'],
        contentUrl: 'http://example.com',
        nonPersonalizedAds: true,
      ),
      listener: listener,
    );

    myBanner.load();
    adWidget = AdWidget(ad: myBanner);

    adContainer = Container(
      alignment: Alignment.center,
      child: adWidget,
      width: myBanner.size.width.toDouble(),
      height: myBanner.size.height.toDouble(),
    );
  }

  @override
  void dispose() {
    super.dispose();
    myBanner.dispose();
  }

  @override
  Widget build(BuildContext context) {
    void _pushPage() {
      Navigator.push(
        context,
        MaterialPageRoute(
          builder: (context) => const SecondPageScreen(),
        ),
      );
    }

    return Column(
      children: [
        Container(
          decoration:
              BoxDecoration(border: Border.all(color: Colors.black, width: 2)),
          child: adContainer,
        ),
        TextButton(onPressed: _pushPage, child: Text('Next Page'))
      ],
    );
  }
}

[Here is the screenshot of the first page, just for quick reference][1] [1]: https://i.stack.imgur.com/Mdi67.png

The second page source

import 'package:flutter/material.dart';

class SecondPageScreen extends StatelessWidget {
  const SecondPageScreen({ Key? key }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('second page')),
      body: Container(

        child: Text('hi')
      ),
    );
  }
}

What I have done:

I tried following the AdMob documentation step by step: https://developers.google.com/admob/flutter/quick-start

And I used the designated test banner ad as shown on the following page: https://developers.google.com/admob/android/test-ads

I registered the app id in adMob

Quite sure that I made the changes in gradle/androidmanifest/pubspec files correctly.

but in vain...

CodePudding user response：

I have this same issue in my application, although I do not fully crash. I do get getSlotFromBufferLocked every time I push to a page that does not have the ad widget on it. If I solve this, I will post back here with a solution.

CodePudding user response：

My friend searched me a page which produced the same exception

https://github.com/flutter/flutter/issues/96875

the problem is solved by downgrading flutter to 2.8.1