[DNSB]

I played with this once using VMWare Workstation. I just tried creating a catalog of the ebooks on my Windows machines and store it in the shared folder and no issues accessing it from any VM (Windows, MacOS or Linux). However, in my earlier testing, when I placed a live library in the shared folder. I could access it from Windows if I created it under Windows. I could access it from Linux (SUSE Tumbleweed) if I created it from there, ditto for MacOS. OTOH, accessing a library from an OS that was not used to create it was very iffy likely due to the differences between how files are handled in different OS.

From your original message, you state that you are attempting to create a catalog (right click on a book, hover on convert books, click on Create a catalog of books in your calibre library) while the rest of your message and the error message seems to show that you are attempting to open a calibre library. Was this library in shared storage and created by Windows and you are accessing it from Linux or vice versa? Did you make sure that you only had one calibre instance running? That is you did not have calibre in Windows and Linux attempting to access the library simultaneously?