Failed to post notification on channel if application is active

Question

I am trying to integrate firebase notifications and I get a "failed to post notification on channel" error when trying to process received notifications.

This issue only happens when application is in the foregroud.

If it is in the background, notifications are displayed without a problem.

I am trying to post to a channel id "12345". I am not sure if this might be the issue, since I am not creating the channel, but if that is the problem, how is it working if the app is in the background?

What am I missing?

I am not using Android 8, and I actually found a snippet that should be used in that case to create a channel:

if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
            int importance = NotificationManager.IMPORTANCE_LOW;
            NotificationChannel notificationChannel = new NotificationChannel(Constants.NOTIFICATION_CHANNEL_ID, Constants.NOTIFICATION_CHANNEL_NAME, importance);
            notificationChannel.enableLights(true);
            notificationChannel.setLightColor(Color.RED);
            notificationChannel.enableVibration(true);
            notificationChannel.setVibrationPattern(new long[]{100, 200, 300, 400, 500, 400, 300, 200, 400});
        }


    Intent intent = new Intent(this, ActivityMain.class);
    intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    // 0 is request code
    PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_ONE_SHOT);



    Uri defaultSoundUri= RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
    NotificationCompat.Builder notificationBuilder =
            new NotificationCompat.Builder(this, Constants.NOTIFICATION_CHANNEL_ID)
                    .setSmallIcon(R.mipmap.ic_launcher)
                    .setContentTitle("FCM Message")
                    .setContentText(messageBody)
                    .setAutoCancel(true)
                    //.setSound(defaultSoundUri)
                    .setContentIntent(pendingIntent);

    NotificationManager notificationManager =
            (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

    // 0 is id of notification
    notificationManager.notify(0, notificationBuilder.build());

Answer 1

My logic above had an error that I missed. The problem was in versions >= 26, because I was creating a channel and then instead of sending the notification to the correct notification manager, I was creating a new instance of the notification manager (view last 2 lines of the question code).

Here is the corrected logic:

private void sendNotification(String messageBody) {

    NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

    // create channel in new versions of android
    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
        int importance = NotificationManager.IMPORTANCE_LOW;
        NotificationChannel notificationChannel = new NotificationChannel(Constants.NOTIFICATION_CHANNEL_ID, Constants.NOTIFICATION_CHANNEL_NAME, importance);
        notificationChannel.enableLights(true);
        notificationChannel.setLightColor(Color.RED);
        notificationChannel.enableVibration(true);
        notificationChannel.setVibrationPattern(new long[]{100, 200, 300, 400, 500, 400, 300, 200, 400});
        notificationManager.createNotificationChannel(notificationChannel);
    }


    // show notification
    Intent intent = new Intent(this, ActivityMain.class);
    intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
    // 0 is request code
    PendingIntent pendingIntent = PendingIntent.getActivity(this, 0, intent, PendingIntent.FLAG_ONE_SHOT);

    Uri defaultSoundUri = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_NOTIFICATION);
    NotificationCompat.Builder notificationBuilder =
            new NotificationCompat.Builder(this, Constants.NOTIFICATION_CHANNEL_ID)
                    .setSmallIcon(R.drawable.icon_contact_purple)
                    .setContentTitle(getString(R.string.app_name))
                    .setContentText(messageBody)
                    .setAutoCancel(true)
                    //.setSound(defaultSoundUri)
                    .setContentIntent(pendingIntent);

    // 0 is id of notification
    notificationManager.notify(0, notificationBuilder.build());

}