In some cases, specially when you already had a previous version of Sanctus Library and you updated to Blender 4.0, you may get an error installing or activating the addon.
This is caused by some old files from Sanctus Library addon not being removed before a fresh install of the new Sanctus Library 2.8 (blender 4.0 compatible) was installed.
Follow the steps to see if that fixes the problem
1. Open Blender and check If there’s any version of Sanctus Library installed in blenders preferences / addons, remove it.
2. Quit blender
3. Check that no folders or files named Sanctus Library are still in the Blender’s addons folder:
If you find any, delete them.
4. Start Blender 4.0 again and install Sanctus Library v2.8 for Blender 4.0
If this doesn’t solve your problem you can contact me