No resource identifier found for attribute '…' in package 'com.app…'

Question

I\'ve imported a project from Eclipse to Android studio. It utilizes a custom view:

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

Answer 1

This also happened to me when a PercentageRelativeLayout https://developer.android.com/reference/android/support/percent/PercentRelativeLayout.html was used and the build was targeting Android 0 = 26. PercentageRelativeLayout layout is obsolete starting from Android O and obviously sometime was changed in the resource generation. Replacing the layout with a ConstraintLayout or just a RelativeLayout solved it.