Originally Posted by Oldpilot
You probably missed the Quote between the first underline and the >
I don't see any missing quote. It reads: <span class="underline">. That's pasted from the original html file.
Sorry, but: There is no error now
in your posting, but the error was there when you pasted it to your epub (or the quote was accidentally deleted afterwards).
Just try it out: turn well-fornmed check off, paste your code to a blank xhtml, remove that quote, save and close the file and open it again and look what sigil did with your code.