This error can happen in case the user was not registered successfully and his profile was not created (which was a bug in old versions of Ultimate Addons)

Solution –

1. Go to Brainstorm Menu
2. Add &author at the end of URL

3. A “Debug” tab will appear. Click on “Reset Site” button.
4. After resetting the site, go to Brainstorm menu and register with your name & email address.

Here is the Video for same-

5. Once successfully registered, you will be able to install updates with just one click.