Do you see these terms,"java.lang.ClassNotFoundException, DexPathList", somewhere along the whole chunk of error message, wherever you rename a file? Simple solution would be to clean build! But do make sure the following are rename accordingly too, 1. class name on Directory 2. class: public class MainActivity extends .... 3. Manifest: <activity android:name=".MainActivity"> 4. XML: tools:context=".MainActivity" https://www.facebook.com/Android-Noob-Reboot-1248769758470969/ https://stackoverflow.com/questions/40493946/refactoring-package-name-breaks-app-with-classnotfoundexception-due-to-not-findi