App won't run under Android Studio 2.0, after upgrading from 1.5

Question

I recently upgraded my Android Studio from 1.5 to 2.0. My app would build and run nicely on Android 1.5. Now, when I try run the app on my smartphone, it gives me this error

Answer 1

Delete build dir

Don't disable Instant Run! It is useful. Instead, try deleting the contents of your build directory, and then rebuilding.

appName/build and/or appName/app/build

Alternatively, clean build

A less brute force option to try is to clean the build.

Build -> Clean Project or Build -> Rebuild Project