In the previous versions of Android, if the app which is currently running in the foreground does not respond, the user is notified. Now, in Android P, the application will just crash without any kind of notification for the user. Among the many changes in Android P, one of the changes is the removal of App Not Responding (ANR) dialogue boxes for foreground apps.
This is almost a shout-out to developers with this feature and Google’s way of asking them to find a resourceful way to deal with an app that is not responding. It’s not necessarily a benefit to users, but it forces developers to pay particular notice to certain problems and make sure that the issue is avoided. Google has discussed the potential solutions to avoid this problem including the AsyncTask API. With Android’s recent limitations on background services, developers should take care of the apps that are not transitioned to a service.
This feature gives the appearance that Android apps are crashing less often and is a good way to not throw up emergency signals in the head of the user. But if the notifications are less visible to the user then developers will have to keep an eye out on their crash tools such as Firebase crash reporting and not direct user feedback.
This isn’t the only change in Android P, Android Oreo introduced the persistent notification when certain apps were running in the background, but Android P now gets rid of that notification entirely.
Via: XDA Developers