I think this is perhaps somehow related to Volumes because I was just able to recreate it.
I looked at the File Manager for the Volume and spotted that some folders and the metadata.db were owned by root instead of Cloudron.
I started changing them one by one via the File Manager but that was tiresome so I open the Web Terminal and ran:
chown -R cloudron:cloudron /library
That fixed the issue on another test I installed, but didn't resolve the issue with my initial install. So I just kept the next test install and moved it books.uniteddiversity.coop which is now working again 🙂 (well, working in a unstable and outdated state 😉 )
I'm pretty sure the issue was created when I rsync'd up a load more books to the Hetzner Storage Box where the Volume actually lives. I'd forgotten that I need to do the chown thing afterwards (and now I'm wondering if I can edit my rsync command to stop me having to chown afterwards...)
Swipe support for reader
Logging of failed opds accesses
Automatic conversion to kepub on kobo sync
Webp format to comic reader supported formats
Title is no longer shortened on book page
Chinese character language texts are no longer shown for english locale
logging on database error
reverse proxy login working again
Detection of invalid email addresses for registering