[:en]
First you should check the directory like other threads described. Then you can check whether the Build tool version matches your SDK version. Else, you can change the buildToolsVersion in build.gradle file.
(e.g. for my project, in build.gradle file, you have:)
android { compileSdkVersion 21 buildToolsVersion “21.1.1” }
and then open you SDK manager, make sure you have the same version of sdk(21.1.1) installed in the selected directory:
If not, install it and restart Android Studio. It works for me.[:]
