Prompt “namespace ‘app’ not bound” when compiling Android studio

The problem is that the root node is missing a declaration.

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

Original:

<?xml version=”1.0″ encoding=”utf-8″?> <menu xmlns:android= ” http://schemas.android.com/apk/res/android ” >

Change to:

<?xml version=”1.0″ encoding=”utf-8″?> <menu xmlns:android= ” http://schemas.android.com/apk/res/android ” xmlns:app= ” http://schemas.android.com/apk/res-auto “>

Can