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

This issue is well known in while using data-binding in a layout.

Assume you want to use some data binding attribute with app: prefix then just adding xmlns:app... will not be enough. layout should be data binding layout wrapped with tag.

Incorrect Approach:

e.g. I imported layout_toolbar_default.xml and using app:toolbarTitle to specify title.

This will show error Unexpected namespace prefix "app" found.

Solution:

Wrap your layout with tag because you are using binding attribute.