Bad notification for start Foreground, Invalid channel for service notification:

Question

So, i have an app on store with 50000 users. Recently i updated my android studio and compiled SDK to 27. I made some changes to support android 8 changes including Notification

Answer 1

You forgot to set channel id for the notification.

if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) builder.setChannelId(youChannelID);

The if statement is optional and depends on your Min SDK level.