I like to publish an ebook created by ebook-convert (4.23.0 on Ubuntu 20.4) on Google PlayStore and their epub validator returns
Error while parsing file: attribute "class" not allowed here; expected attribute "dir", "lang", "version" or "xml:lang".
for every chapter. I found out removing class attribute from the html tag solves the problem.
<html xmlns="http://www.w3.org/1999/xhtml" class="calibre">
At https://bugs.launchpad.net/calibre/+bug/1897582 I learnt that it might have to do with a css attribute that is clinged to the html element. But I don't find any style information, that I set on the html element. I just pass in a markdown file with additional CSS set, but this contains nothing for the html tag. And if I omit it, I get the same error.
Is is possible to tell ebook-convert not to add the class somehow?
My full command I send is:
ebook-convert /tmp/ebookmaker_tmpfile.epub.md path/to/book.epub --language "de" --title "Booktitle" --authors "Author" --output-profile "kindle" --book-producer "ewer" --comments "MIT" --isbn "9798683069964" --pubdate "<DATE>" --publisher "Michael Schmidt" --extra-css "[path to]/media/global.css" --embed-all-fonts --line-height "22" --change-justification "justify" --formatting-type "markdown" --toc-title "Inhalt" --level1-toc "//h:h2" --use-auto-toc
The validator that returns the error message is also online here: http://