Crash is observed at approximately in 3-5% users, in the rest updates works as expected.

Launch manager when Activity creates

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        UpdatesManager.getInstance().checkUpdates(this);
    }

    @Override
    protected void onResume() {
        super.onResume();
        UpdatesManager.getInstance().proposeToInstallDownloadedUpdate(this);
    }

    @Override
    protected void onStop() {
        UpdatesManager.getInstance().unregisterListener();
        super.onStop();
    }

    @Override
    protected void onDestroy() {
        UpdatesManager.getInstance().removeInstance();
        super.onDestroy();
    }
}

Actually manager

public class UpdatesManager {

    private static volatile UpdatesManager updatesManager = null;
    private AppUpdateManager appUpdateManager;
    private InstallStateUpdatedListener installStateUpdatedListener;
    private ActivityResultLauncher<IntentSenderRequest> activityResultLauncher;

    private UpdatesManager() {
    }

    public static synchronized UpdatesManager getInstance() {
        if (updatesManager == null) {
            updatesManager = new UpdatesManager();
        }
        return updatesManager;
    }

    public void checkUpdates(MainActivity mainActivity) {
        registerResultLauncher(mainActivity);
        appUpdateManager = AppUpdateManagerFactory.create(mainActivity);
        Task<AppUpdateInfo> appUpdateInfoTask = appUpdateManager.getAppUpdateInfo();
        if (activityResultLauncher != null) {
            appUpdateInfoTask.addOnSuccessListener(new OnSuccessListener<AppUpdateInfo>() {
                @Override
                public void onSuccess(AppUpdateInfo appUpdateInfo) {
                    if (appUpdateInfo.updateAvailability() == UpdateAvailability.UPDATE_AVAILABLE && appUpdateInfo.isUpdateTypeAllowed(AppUpdateType.FLEXIBLE)) {
                        //
                        //
                        appUpdateManager.startUpdateFlowForResult(appUpdateInfo, activityResultLauncher, AppUpdateOptions.newBuilder(AppUpdateType.FLEXIBLE).build());
                    }
                }
            });

            installStateUpdatedListener = new InstallStateUpdatedListener() {
                @Override
                public void onStateUpdate(@NonNull InstallState state) {
                    if (state.installStatus() == InstallStatus.DOWNLOADED) {
                        startAlertUpdateDownloaded(mainActivity);
                    }
                }
            };
            appUpdateManager.registerListener(installStateUpdatedListener);
        }
    }

    private void registerResultLauncher(MainActivity mainActivity) {
        activityResultLauncher = mainActivity.registerForActivityResult(new ActivityResultContracts.StartIntentSenderForResult(), new ActivityResultCallback<ActivityResult>() {
            @Override
            public void onActivityResult(ActivityResult result) {
                if (result.getResultCode() != RESULT_OK) {
                    Log.d("UM", "onActivityResult code: " + result.getResultCode());
                }
            }
        });
    }

    public void unregisterListener() {
        if (appUpdateManager != null && installStateUpdatedListener != null) {
            appUpdateManager.unregisterListener(installStateUpdatedListener);
        }
    }

    public void removeInstance() {
        if (activityResultLauncher != null) {
            activityResultLauncher = null;
        }
        if (appUpdateManager != null) {
            appUpdateManager = null;
        }
        if (installStateUpdatedListener != null) {
            installStateUpdatedListener = null;
        }
        if (updatesManager != null) {
            updatesManager = null;
        }
    }

}

Looking at report we can see that crash caused by line 68

Fatal Exception: java.lang.NullPointerException: Attempt to invoke
virtual method ‘java.lang.Class java.lang.Object.getClass()’ on a null
object reference
at com.domainName.appName.UpdatesManager$1.onSuccess(UpdatesManager.java:68)
at com.domainName.appName.UpdatesManager$1.onSuccess(UpdatesManager.java:62)
at com.google.android.gms.tasks.zzm.run(com.google.android.gms:play-services-tasks@@18.1.0:1)
at android.os.Handler.handleCallback(Handler.java:900)
at android.os.Handler.dispatchMessage(Handler.java:103)
at android.os.Looper.loop(Looper.java:219)
at android.app.ActivityThread.main(ActivityThread.java:8676)
at java.lang.reflect.Method.invoke(Method.java)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:513)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1109)

Line 68 at checkUpdates function

appUpdateManager.startUpdateFlowForResult(appUpdateInfo, activityResultLauncher, AppUpdateOptions.newBuilder(AppUpdateType.FLEXIBLE).build());

If I understand right, appUpdateManager object is null here. I suspect something wrong with Activity LifeCycle but can’t find mistake.