Android Studio - mergeDebugResources exception

You may have a corrupted .9.png in your drawables directory

inside your project directory, run:

./gradlew clean build

or from Android Studio select:

Build > Clean Project

Updated: As @VinceFior pointed out in a comment below

It happens to me only when modifying the XML files on the project. If you rebuild the entire project before running (Build > Rebuild Project) it doesn't show up anymore.