Android Studio + Volley = NoClassDefFound?
Answer : Exception java.lang.NoClassDefFoundError: com.google.android.gms.common.AccountPicker Found the fix here. Basically, open a command prompt (or terminal) and navigate to your project directory. Use the following command on Windows: For Windows users: gradlew.bat clean And for mac users type: ./gradlew clean Then reload Android Studio and try again!