One of our users submitted an EPUB book for inclusion into the iBookstore. The file passed the epubcheck validation test. But this file was rejected by Apple with the following error message:
Apple ERROR ITMS-4000: Line 89 column 63: bad character content for element at XPath/package/book/assets/asset[2]/data_file/file_name.
I googled for this error. The only site page where it is mentioned is a bug report page of Calibre:
http://bugs.calibre-ebook.com/ticket/5773
I do not have the "guilty" EPUB file (there are privacy concerns I guess).
Can anyone say what this error could mean?
Thanks.