I recently attempted to migrate my Eclipse project over to Android Studio. All went well until I attempted to run the project and an error came up:
Uploading
I just ran into this problem, even without transferring from Eclipse, and was frustrated because I kept showing no compile or packageDebug errors. Somehow it all fixes itself if you clean and THEN run packageDebug.
Open up a commandline, and in your project's root directory, run:
./gradlew clean packageDebug
Obviously, if either of these steps shows errors, you should fix those...But when they both succeed you should be able to find the apk when you navigate the local path -- and even better, your program should install/run on the device/emulator!