I'm getting this error with several LIT to ePub conversions. I found this thread
https://www.mobileread.com/forums/showthread.php?t=53311 on the issue, but the solution/hint provided is Greek to me (Calibre novice and no experience with html whatsoever).
Can anyone explain how to 'pre-edit' the problematic LIT files so Calibre can split it and make the ePub?