Bugzilla – Bug 916
The validator has started to issue an errore for the doctype legacy string
Last modified: 2012-09-21 16:06:56 CEST
See this bug: https://www.w3.org/Bugs/Public/show_bug.cgi?id=16516
In the HTML5 validator at http://validator.w3.org (as opposed to the http://validator.w3.org/nu/ valiator), this bug is not seen.
Thanks for reporting.