If you try to update your old Android Studio to Android Studio 1.2 RC 2 you may get this error:
The following SDK components were not installed: …
Most commons errors are for this components:
extra-android-m2repository,tools,addon-google_apis-google-21,android-21,sys-img-x86-addon-google_apis-google-21,source-21,extra-google-m2repository…
After this error the process of installation it’s stopped running.
To fix this you need to take a look to this path: …\AppData\Local\Android\sdk1
Start the: SDK Manager.exe application to update all your SDK components…
…or try to run the android.bat command from tools folder: tools\android.bat update sdk –no-ui
After that, the installation/update of Android Studio will be like in the next images.
Then make all settings
