Xamarin forms – Android Firebase notification never showed

In a xamarin forms project, I have added Firebase plugin to my project to do push notification.

The plugin works well in my IOS project. I can see the data in the output and when the app is in background the notification pops up.

My problem:
In my Android project the notification never pop up. I can see in output console the data send on Firebase platform, but when the app is in background the pop up does not appear and I have this error when I put the value com.AppName.urgent in my Strings.xml file

[FirebaseMessaging] Notification Channel set in AndroidManifest.xml has not been created by the app. Default value will be used.

I have not error when I put the value default but the notification still not appear

How can I make the notification appear on Android ?

Here is my code :

the strings.xml file in my android project :

<?xml version="1.0" encoding="UTF-8" ?>
<resources>
<string name="notification_channel_id">default</string>
</resources>

My Android Files : MainActivity

namespace AppName.Droid
{
    [Activity(Label = "AppName", Icon = "@mipmap/icon", Theme = "@style/MainTheme", ConfigurationChanges = ConfigChanges.ScreenSize
        | ConfigChanges.UiMode | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize
        | ConfigChanges.Orientation, ScreenOrientation = ScreenOrientation.Portrait
         )]
    public class MainActivity : global::Xamarin.Forms.Platform.Android.FormsAppCompatActivity
    {
        internal static MainActivity Instance { get; private set; }

        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);

            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
            global::Xamarin.Forms.Forms.Init(this, savedInstanceState);
            LoadApplication(new App());
            FirebasePushNotificationManager.ProcessIntent(this, Intent);

        }



        protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
        {
            base.OnActivityResult(requestCode, resultCode, data);

            Stormlion.ImageCropper.Droid.Platform.OnActivityResult(requestCode, resultCode, data);
        }

        public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
        {

          
            Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);

            base.OnRequestPermissionsResult(requestCode, permissions, grantResults);

            switch (requestCode)
            {
                case AndroidMicrophoneService.RecordAudioPermissionCode:
                    if (grantResults[0] == Permission.Granted)
                    {
                        micService.OnRequestPermissionResult(true);
                    }
                    else
                    {
                        micService.OnRequestPermissionResult(false);
                    }
                    break;
            }

        }


    }
}

My Firebase file : MainApplication

[Application]
    public class MainApplication : Application
    {
        public MainApplication(IntPtr handle, JniHandleOwnership transer) : base(handle, transer)
        {
        }

        public override void OnCreate()
        {
            base.OnCreate();



            //Set the default notification channel for your app when running Android Oreo
            if (Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.O)
            {


                //Change for your default notification channel id here
                FirebasePushNotificationManager.DefaultNotificationChannelId = "FirebasePushNotificationChannel";

                //Change for your default notification channel name here
                FirebasePushNotificationManager.DefaultNotificationChannelName = "General";

             

            }




            //If debug you should reset the token each time.
#if DEBUG
            FirebasePushNotificationManager.Initialize(this, true);
#else
            FirebasePushNotificationManager.Initialize(this,false);
#endif

            //Handle notification when app is closed here
            CrossFirebasePushNotification.Current.OnNotificationReceived += (s, p) =>
            {


            };


        }
    }

In my app.xaml.cs :

public App()
{
    InitializeComponent();
    MainPage = new LInPage();

    }


    // Firebase Notifcation
    CrossFirebasePushNotification.Current.OnTokenRefresh += (s, p) =>
    {
        System.Diagnostics.Debug.WriteLine($"MyTOKEN : {p.Token}");
    };
    CrossFirebasePushNotification.Current.OnNotificationReceived += (s, p) =>
    {

        System.Diagnostics.Debug.WriteLine("Received");
        foreach (var data in p.Data)
        {
            System.Diagnostics.Debug.WriteLine($"Mydata {data.Key} : {data.Value}");
        }

    };
    CrossFirebasePushNotification.Current.OnNotificationOpened += (s, p) =>
    {
        System.Diagnostics.Debug.WriteLine("Opened");
        foreach (var data in p.Data)
        {
            System.Diagnostics.Debug.WriteLine($"Opended {data.Key} : {data.Value}");
        }


    };

}

SplashActivity.cs (Opening Screen Image) :

namespace AppName.Droid
{
    [Activity(Theme = "@style/MyTheme.Splash", MainLauncher = true, NoHistory = true)]
    public class SplashActivity : Activity
    {
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);

            // Create your application here
        }

        protected override async void OnResume()
        {
            base.OnResume();
            await SimulateStartup();
        }

        async Task SimulateStartup()
        {

            await Task.Delay(1000); // Simulate a bit of startup work.
            StartActivity(new Intent(Application.Context, typeof(MainActivity)));
        }
    }
}

My AndroidManifest.xml :

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" android:versionName="98.0" package="com.AppName" android:versionCode="98">
    <uses-sdk android:minSdkVersion="21" android:targetSdkVersion="31" />
    <application android:label="AppName" android:theme="@style/MainTheme" android:icon="@mipmap/icon_round">
        <activity android:name="com.theartofdev.edmodo.cropper.CropImageActivity" android:theme="@style/Base.Theme.AppCompat" />
        <meta-data android:name="com.google.firebase.messaging.default_notification_channel_id" android:value="@string/notification_channel_id" />
        <!-- optional (needed if default theme has no action bar) -->
        <service android:name="crc6494e14b9856016c30.PNFirebaseMessagingService" android:exported="false">
            <intent-filter>
                <action android:name="com.google.firebase.MESSAGING_EVENT" />
            </intent-filter>
        </service>
    </application>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.RECORD_AUDIO" />
    <uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS" />
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-feature android:name="android.hardware.location" android:required="false" />
    <uses-feature android:name="android.hardware.location.gps" android:required="false" />
    <uses-feature android:name="android.hardware.location.network" android:required="false" />
    <queries>
        <intent>
            <action android:name="android.intent.action.SENDTO" />
            <data android:scheme="mailto" />
        </intent>
    </queries>
</manifest>

I have followed these links but without success :

• W/FirebaseMessaging: Missing Default Notification Channel metadata in AndroidManifest. Default value will be used