I'm remediating some VERY old EPUB files, and got this error:

ERROR | OPF-032 | /content.opf (line 64, col 77) | Guide references "https://2694f716-dddd-4b2b-bbfe-64990fe68f69.epubcheck.w3c.org/OEBPS/images/cover.jpg" which is not a valid "OPS Content Document".

Obviously I'll change the guide item target to the cover XHTML page, but I'm sure it's not intended behaviour that this shows an HTTPS URL path. This happens in EPUB Check 5.0.1 and 5.1.1, I believe the error first appeared in the former. Seen this on multiple files now, though this particular file was created 13 years ago.