After upgrade all menu entries pointing to k2 articles failed, yet the url of the articles reamined the same.

for example:

My article url is:

verificiencia.com/quackwatch/7-quackwatch/172-vitamina-c-las-dosis-altas-previenen-los-resfriados.html

But after update the menu linking to the article points to:

verificiencia.com/quackwatch/quackwatch/172-vitamina-c-las-dosis-altas-previenen-los-resfriados.html

So it reports 404, not found.

Somehow the part "7-quackwatch" becames "quackwatch", just in the menu.

The same goes to all my k2 articles. Other parts of the site not K2 works.

I downgraded to v2.09 and the site is working now. For some reason... both url work now.

(note: I am looking for the precvious version K2 v2.10.2)

Did you try changing the main k2 Settings. User SEO tab, then under Custom SEF URLs there is option "Use the category ID in the URL" Not sure why it would have changed in upgrade, but you may need to just turn that on if you want the ID in there.