If you get the following error while trying to use an update site:
It means that you have wrong login credentionals registered and you need to reset these. Follow the following steps:
- Select "Window -> Preferences".
- Select "General -> Security -> Secure Storage".
- Select the "Content" panel.
- Click [Default Secure Storage].
- Click "Delete".
- Restart Studio.
This will reset all your passwords and the next time you try to contact the site you will be asked for new username and password.