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.

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.

Google has kept the System UI Tuner hidden in Android Marshmallow and Android N, at least for now, simply because these settings are experimental and could have some bugs.