If you are getting "Unable to save plugin settings" or "unable to save settings" Error window,
and you have tried all of the other solutions listed here, but they don't work for you, try the following:
- Invalidate Cache: but don't select restart yet, select just "invalidate".
- Close project and then exit Studio
- If you have a previous backup of your Settings folder, restore it now.
If not, you will need to Delete your settings folder. For example, in Windows:
/ < USER_HOME_DIR >/.AndroidStudioPreview3.2
or on Mac :
/Users/<USER_NAME>/Library/Preferences/.AndroidStudioPreview3.2
- Delete the .idea folder for your project
- Re-launch Android studio, but this time select import project
Android Studio will re-index your project, but now the error will be gone.
After Android Studio has completed a Gradle Sync, it's probably a good idea to also make a backup of the settings folder