Hello everyone, I am new to this forum and community. I am an Indi amateur publisher in the process of creating an EPUB file for 'publishing. I am using Calibre 3.41.3 to produce an EPUB 3 for submission of a book to IngramSpark that requires EPUB 3 format (won't accept EPUB 2).
When checking the EPUB 3 file with "EPUB Validator (beta)" at
http://validator.idpf.org/application/validate I get the following message:
WARNING - content.opf: XHTML Content Document file name 'index_split_000.html' should have the extension '.xhtml'.
These errors appear at every page break in my source document (docx format). There is a footnote on the results page that reads - Validated using EPUBCheck version 4.1.1. (an EPUB 2 file from the same input file passes without any errors).
Is there a setting in Calibre that overcomes this problem with the extension file name?