disclaimer: I'm still relatively new to Emacs.
When I open an Epub on MS Windows, Emacs opens it using Zip-Archive mode and displays its content (which is normal afaik).
However, when I start nov-mode, encoded characters are displayed and I got an error of Wrong type argument: stringp, nil in the minibuffer.
What should I do? Where should I look?
EDIT You can find sources of nov here

