[KevinH]

Nothing looks out of place.

But above you said some errors were in the PDF which is not the same as the OPF.

Have you tried changing en-GB to just en in case they only accept a limited number of languages?

I would try loading your epub in Sigil or calibre and using Doitsu's epubcheck plugin and report all errors it reports about the opf with full info here.

But if this is feiyr.com, I thought we already determined their epub validation was very broken a few months back, at least that is what I remember.

Your package tag does seems to define a number of xmlns prefixes that are not used anyplace and could be deleted.

You can remove the calibre:author_link_map line as epub2 style metadata is ignored under epub3 specs. Same with the Sigil version info.


Just guessing but perhaps the opf is just not well-formed and parsing it is broken? Or maybe you incorrectly typed in the xmlns:dc definition. You should check that but at first glance it appears to be correct.