On Android 8.1 API 27 notification does not display

Question

I get Toast on Android 8.1 API 27:

Developer warning for package \"my_package_name\"
Failed to post notification on ...

L

Answer 1

Andy's answer is working however I wanted to avoid to deprecated Builder and follow the FireBase Quickstart Project. I just added code before notify from manager.

String channelId = "default_channel_id";
String channelDescription = "Default Channel";
// Since android Oreo notification channel is needed.
//Check if notification channel exists and if not create one
if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {
    NotificationChannel notificationChannel = notificationManager.getNotificationChannel(channelId);
    if (notificationChannel == null) {
        int importance = NotificationManager.IMPORTANCE_HIGH; //Set the importance level
        notificationChannel = new NotificationChannel(channelId, channelDescription, importance);
        notificationChannel.setLightColor(Color.GREEN); //Set if it is necesssary
        notificationChannel.enableVibration(true); //Set if it is necesssary
        notificationManager.createNotificationChannel(notificationChannel);
    }
}

//notificationManager.notify as usual

Edit: They removed the channel exist check from example I am not sure why.