HTML ARIA validation issues (HTML5)

Question

I pretty much make sure my website(s) always validates.

So today, after changing a certain item on my website, I ran the W3C validator once again.

And suddenly got about 20 errors - which weren't there on thursday (2 days ago).

(For my validation I chose HTML5 / UTF8 - just like last time)

For some reason I now get a:

Element li is missing one or more of the following attributes: aria-checked, aria-expanded, aria-valuemax, aria-valuemin, aria-valuenow, aria-valuetext, role."-error for every list item I use.

Is ARIA mandatory, and if so why do I suddenly get these errors - when I did not two days ago?

It could be that I'm overlooking something. My website can be found here: http://www.project-voorbeeld3.be/

I have to admit, ARIA is new to me at this point - but I've looked through quite a lot of articles about it, and I just can't seem to figure out what is wrong.

Any clues would be welcome!

Answer 1

As of today, it seems like ARIA related HTML5 errors are disappeared.

ARIA validation can be made from this website: http://validator.w3.org/nu/
But note this warning:

The W3C Nu Markup Validation Service support for ARIA checking is a work in progress, so cannot be wholly relied upon to provide the correct results.

Answer 2

Seems like a false alarm (just somebody's mistake). Found this message from http://lists.w3.org

Answer 3

Making ARIA mandatory in HTML5 would be utterly stupid. There are sites that do not in fact need any ARIA functionality, and this would mean that all the webpages that used to validate have to be re-done: an awful amount of pointless work. On the other hand, it is rather difficult to ignore the ARIA errors while I am actually using the validator to find real problems in my HTML. ARIA is good but it must be optional, not mandatory. I hope they are goint to remove that nonsense from the validator soon.