Android Studio: Error parsing XML & URI is not registered

Question

After adding a new Activity to my project I get following error while compiling the layout

Gradle: Error parsing XML: not well-formed (invalid token)<

Answer 1

My issue was creating new resource directory for some animation work. The files were .xml and I chose file type as "xml". I got this problem. Changing the file type to "values" and the problem went away. No idea why, could someone explain this to me? I'm using Android Studio on an iMac.