Steam has released the first version of 2.80 Official and I changed versions from RC3 to Official. I knew that Artfunkel released BleST 3.0 and I attempted to do a Check For Updates using Blender 2.80 (Off) and BlesT 2.11.0b1. I ended up with the attached error.

https://i.imgur.com/ipSeE1Z.jpg

To fix the error I had to manually remove the old version of BleST 2.11.0b1 (Userpref, AddOns, Blender Source Tools (expand), click Remove)

Use the link on the group main page to go to the BleST 3.0 site and download,

Then reinstall 3.0 to Blender addons (UserPref, Addons, install from file, point to the download new version zip file)

Check for updates now appears to work.