I get this error when starting a foreground service:

Java.Lang.RuntimeException: Bad notification for startForeground: java.lang.RuntimeException: invalid service notification: Notification(channel=channelSocketIOService pri=0 contentView=null vibrate=null sound=null defaults=0x0 flags=0x42 color=0x00000000 vis=PRIVATE)
  --- End of managed Java.Lang.RuntimeException stack trace ---
android.app.RemoteServiceException: Bad notification for startForeground: java.lang.RuntimeException: invalid service notification: Notification(channel=channelSocketIOService pri=0 contentView=null vibrate=null sound=null defaults=0x0 flags=0x42 color=0x00000000 vis=PRIVATE)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1945)
    at android.os.Handler.dispatchMessage(Handler.java:107)
    at android.os.Looper.loop(Looper.java:214)
    at android.app.ActivityThread.main(ActivityThread.java:7356)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
 /end;

In service class:

private void RegisterForegroundService()
{
    Notification notification = new NotificationCompat.Builder(this, $"ServiceNotifications")
        .SetOngoing(true)
        .Build();

    StartForeground(462, notification);
}

Thanks for your help

CodePudding user response：

You need to create a default notification channel in Android 8 and above. Or else you will get this error. More details at startForeground fail after upgrade to Android 8.1

CodePudding user response：

From document Create and Manage Notification Channels ,we will know :

Starting in Android 8.0 (API level 26), all notifications must be assigned to a channel. For each channel, you can set the visual and auditory behavior that is applied to all notifications in that channel. Then, users can change these settings and decide which notification channels from your app should be intrusive or visible at all.

In xamarin android platform, you can check document Notifications in Xamarin.Android.

And there is a sample included in above code. You can check it here : https://github.com/xamarin/monodroid-samples/tree/master/LocalNotifications .

The main code is:

public class MainActivity : AppCompatActivity
{
    // Unique ID for our notification: 
    static readonly int NOTIFICATION_ID = 1000;
    static readonly string CHANNEL_ID = "location_notification";
    internal static readonly string COUNT_KEY = "count";

    // Number of times the button is tapped (starts with first tap):
    int count = 1;

    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);
        SetContentView(Resource.Layout.Main);

        CreateNotificationChannel();

        // Display the "Hello World, Click Me!" button and register its event handler:
        var button = FindViewById<Button>(Resource.Id.MyButton);
        button.Click  = ButtonOnClick;
    }

    // Handler for button click events.
    void ButtonOnClick(object sender, EventArgs eventArgs)
    {
        // Pass the current button press count value to the next activity:
        var valuesForActivity = new Bundle();
        valuesForActivity.PutInt(COUNT_KEY, count);

        // When the user clicks the notification, SecondActivity will start up.
        var resultIntent = new Intent(this, typeof(SecondActivity));

        // Pass some values to SecondActivity:
        resultIntent.PutExtras(valuesForActivity);

        // Construct a back stack for cross-task navigation:
        var stackBuilder = TaskStackBuilder.Create(this);
        stackBuilder.AddParentStack(Class.FromType(typeof(SecondActivity)));
        stackBuilder.AddNextIntent(resultIntent);

        // Create the PendingIntent with the back stack:            
        var resultPendingIntent = stackBuilder.GetPendingIntent(0, (int) PendingIntentFlags.UpdateCurrent);

        // Build the notification:
        var builder = new NotificationCompat.Builder(this, CHANNEL_ID)
                      .SetAutoCancel(true) // Dismiss the notification from the notification area when the user clicks on it
                      .SetContentIntent(resultPendingIntent) // Start up this activity when the user clicks the intent.
                      .SetContentTitle("Button Clicked") // Set the title
                      .SetNumber(count) // Display the count in the Content Info
                      .SetSmallIcon(Resource.Drawable.ic_stat_button_click) // This is the icon to display
                      .SetContentText($"The button has been clicked {count} times."); // the message to display.

        // Finally, publish the notification:
        var notificationManager = NotificationManagerCompat.From(this);
        notificationManager.Notify(NOTIFICATION_ID, builder.Build());

        // Increment the button press count:
        count  ;
    }

    void CreateNotificationChannel()
    {
        if (Build.VERSION.SdkInt < BuildVersionCodes.O)
        {
            // Notification channels are new in API 26 (and not a part of the
            // support library). There is no need to create a notification 
            // channel on older versions of Android.
            return;
        }

        var name = Resources.GetString(Resource.String.channel_name);
        var description = GetString(Resource.String.channel_description);
        var channel = new NotificationChannel(CHANNEL_ID, name, NotificationImportance.Default)
                      {
                          Description = description
                      };

        var notificationManager = (NotificationManager) GetSystemService(NotificationService);
        notificationManager.CreateNotificationChannel(channel);
    }
}