Once you’ve reset the app settings on your Android system, restart your device and check for the Android System UI has stopped issue. Fix #7: Install software updates.

Encountering the "System UI isn't responding" error on your Android phone can happen when the user interface responsible for displaying your home screen ...

Another trick that some Android users discovered to fix System UI has stopped error is by removing widgets. A widget is a tiny screen of a particular app installed on your device.