invalid channel for service notification: Notification

My code works exactly fine as long as I use the Android Emulator to test it, but once I build it and try to use it on my mobile phone I get the following error:

    An uncaught Exception occurred on "main" thread.
Bad notification for startForeground: java.lang.RuntimeException: invalid channel for service notification: Notification(channel=channel_01 pri=0 contentView=null vibrate=null sound=null defaults=0x0 flags=0x40 color=0x00000000 vis=PRIVATE)

StackTrace:
android.app.RemoteServiceException: Bad notification for startForeground: java.lang.RuntimeException: invalid channel for service notification: Notification(channel=channel_01 pri=0 contentView=null vibrate=null sound=null defaults=0x0 flags=0x40 color=0x00000000 vis=PRIVATE)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1760)
    at android.os.Handler.dispatchMessage(Handler.java:106)
    at android.os.Looper.loop(Looper.java:201)
    at android.app.ActivityThread.main(ActivityThread.java:6806)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:547)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:873)

this is my code:

@JavaProxy('org.nativescript.nstestandroid.ForegroundService')
class ForegroundService extends android.app.Service {
    onStartCommand(intent, flags, startId) {
        console.log('onStartCommand');
        super.onStartCommand(intent, flags, startId);
        return android.app.Service.START_STICKY;
    }

    onCreate() {
        console.log('onCreate')
        super.onCreate();
        this.startForeground(1, this.getNotification());
    }



 private getNotification() {
        const channel = new android.app.NotificationChannel(
            'channel_01',
            'ForegroundService Channel', 
            android.app.NotificationManager.IMPORTANCE_DEFAULT
        );
       // <const notificationManager = this.getSystemService(android.content.Context.NOTIFICATION_SERVICE) as android.app.NotificationManager;
        //notificationManager.createNotificationChannel(channel);
        const builder = new android.app.Notification.Builder(this.getApplicationContext(), 'channel_01');

        return builder.build();
    }

Solution

you need to create NotificationChannel before posting into it new Notification. Smth like this:

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    CharSequence name = getString(R.string.channel_name);
    String description = getString(R.string.channel_description);
    int importance = NotificationManager.IMPORTANCE_DEFAULT;
    NotificationChannel channel = new NotificationChannel(CHANNEL_ID, name, importance);
    channel.setDescription(description);

    // Don't see these lines in your code...
    NotificationManager notificationManager = getSystemService(NotificationManager.class);
    notificationManager.createNotificationChannel(channel);
}

you are only creating new channel (as object), but never call createNotificationChannel

you probably have created notification channel on emulator, but not on device. there is also a chance that some devices with earlier OS versions may auto-create "default" notification channel for compatibility purposes, but newer OS versions may require channel creation before showing notification

some guide in HERE