The error reported in
this thread is due to to changes:
https://github.com/kovidgoyal/calibr...12dbc0d7d37f45 and
https://github.com/kovidgoyal/calibr...912468e0494a0a. And they are to add epub3 metadata support. As kepubs can be either epub2 or epub3, my first thought is to fix this with:
Code:
f = self.rationalize_cover3 if opf.package_version >= 3.0 else self.rationalize_cover2
self.removed_cover = f(opf, log)
I have done some quick tests, and is seems to work. And,
https://store.kobobooks.com/ebook/girl-from-above-1 is a free DRM epub3 and works with the above code.