After upgrade message states:
Failed to refresh Gradle project \'XXX\' The project is using an unsupported version of the Android Gradle plug-in (0.8.3). Ve
When I updated to Android Studio 1.0 I found that I need to update to use 1.0.0 version of gradle.
I had
dependencies { classpath 'com.android.tools.build:gradle:1.0.0-rc2'
I changed it to remove the "-rc2"
dependencies { classpath 'com.android.tools.build:gradle:1.0.0'