As we keep a local copy of the W3C validator due to the volume of requests it can get out of sync with the latest build. We are aware that the W3C validation test needs updating and are working on that now. The changes made only affect a small number of HTML5 sites; most users will not notice any changes as their W3C validator test results are accurate. We will update this status once we have made the changes.
[14:51] We have updated our W3C test to the latest version.