Unexpected namespace prefix “app” found for tag RelativeLayout - Android?

Question

I need to use BottomSheetBehavior with ScrollView but it says to me :

Unexpected namespace prefix \"app\" found for tag RelativeLayout
         


        

Answer 1

xmlns:app="http://schemas.android.com/apk/res-auto"

This is set multiple times. Both in CoordinatorLayout and RelativeLayout. Remove the one in RelativeLayout. Declaring once in the file will suffice.