* Error running Gradle:
NDK is missing a "platforms" directory.
If you are using NDK, verify the ndk.dir is set to a valid NDK directory. It is currently set to
FAILURE: Build failed with an exception.
Build File 'C:\Users\~UserName~\AndroidStudioProjects\sandwich\android\app\build.gradle'
If you face this error, make sure if NDK is available in the given path or not., The path is present in the error, which is something like C:\Users\~UserName~\AppData\Local\Android\sdk\ndk-bundle..
Verify if the files exist there, otherwise change that from project structure.
To access Project Structure, go to File -> Other Settings -> Default Project Structure. It will show a window as below.
Hope this helps.