Failed to post notification on channel “null” Target Api is 26

Question

Two log showing

1: Use of stream types is deprecated for operations other than volume control

2: See the documentation of setSound() for what to use instea

Answer 1

This issue is related to the old FCM version.

Update your dependency to com.google.firebase:firebase-messaging:15.0.2 or higher.

This will fix the error

failed to post notification on channel null

when your app receives notifications in the background because now Firebase provides a default notification channel with basic settings.

But you also can specify the default Notification Channel for FCM in the manifest.

<meta-data
android:name="com.google.firebase.messaging.default_notification_channel_id"
android:value="@string/default_notification_channel_id"/>

To learn more here

Answer 2

First create the notification channel:

public static final String NOTIFICATION_CHANNEL_ID = "4655";
//Notification Channel
        CharSequence channelName = NOTIFICATION_CHANNEL_NAME;
        int importance = NotificationManager.IMPORTANCE_LOW;
        NotificationChannel notificationChannel = new NotificationChannel(NOTIFICATION_CHANNEL_ID, 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 notificationManager = (NotificationManager) context.getSystemService(Context.NOTIFICATION_SERVICE);
        notificationManager.createNotificationChannel(notificationChannel);

then use the channel id in the constructor:

final NotificationCompat.Builder builder = new NotificationCompat.Builder(context, NOTIFICATION_CHANNEL_ID)
                .setDefaults(Notification.DEFAULT_ALL)
                .setSmallIcon(R.drawable.ic_timers)
                .setVibrate(new long[]{100, 200, 300, 400, 500, 400, 300, 200, 400})
                .setSound(null)
                .setContent(contentView)
                .setPriority(NotificationCompat.PRIORITY_DEFAULT)
                .setLargeIcon(picture)
                .setTicker(sTimer)
                .setContentIntent(timerListIntent)
                .setAutoCancel(false);