I've reproduced an issue with the 'OpenACS Bootstrap 5 Theme' Administration page that causes the site styles to break upon server restart. This is happening with package version 5.10.1d2
Here are the steps to reproduce
1. Assuming your site is currently loading bootstrap via the CDN
2. Check you do not have a bootstrap folder in the directory packages/openacs-bootstrap5-theme/www/resources/
3. Visit the 'OpenACS Bootstrap 5 Theme' Administration page from the Site Wide Administration main page.
4. The page should report that you are loading bootstrap via the cdn.
5. Check your directory again packages/openacs-bootstrap5-theme/www/resources/
Notice now there is a bootstrap folder with an empty folder tree of bootstrap/bootstrap@5.2.0/dist/
6. Restart your OpenACS server instance
Due to the existence of that directory it now will attempt to load the styles and js for bootstrap locally when you have the following in your ThemeCSS
{-href urn:ad:css:bootstrap5 -media all -order 1}
The Administration page shouldn't be creating an empty folder tree and/or the check on startup to detect whether to use CDN or local should check for a non-empty directory path.