Hi! I think this might be easy to reproduce, and I'm not sure if "whose to blame" is okular or some backend perhaps that libepub1(?) thingie? Anyways, here goes. I have a Raspberry Pi hooked to a tv next to my bed where I usually read books and suchlike. Many files are located on my desktop PC running Windows, so I have this mounted over SMB. If I try to open an .epub file over the SMB, I get a error message that it won't load. Other files (e.g. PDF files) loads perfectly though. At first I thought that the .epub backend was broken as a whole, but then I tried "cp /win10computer/share/book.epub ~/books/ ; okular ~/books/book.epub" and then the exact same file loads just fine. It's just that I get an error when I try to open it with the SMB mount point, and (like I said) it only seems to affect .epub files, whilst I can load for instance .pdf files just fine. Cheers!
> If I try to open an .epub file over the SMB, Can you please explain what this *exactly* means? Are you using dolphin to open the file? or okular file menu? or okular from the command line? Also is that "over the SMB" using a mountpoint or are you using a KIO url like smb:/ ?