I have encountered the same issue after upgrading to 6.2.6
My understanding is that the issue presents itself when you use SessionPageStatePersister instead of the default in-page persister, to keep pages' viewstates in the Session.
The SessionPageStatePersister replaces the default in-page persister by the Telerik's compression mechanism, if you use it, or, if you use a custom code to replace the default one with SessionPageStatePersister, to eliminate VIEWSTATE gibberish in the page
The DotNetNuke.Framework.ServicesFrameworkImpl.RegisterAjaxAntiForgery(Page page) uses the MS System.Web.Mvc.HtmlHelper.AntiForgeryToken, which, in turn, apparently uses PageStatePersister, which will be implemented via SessionPageStatePersister in the above cases. (see the last paragraph of
http://msmvps.com/blogs/luisabreu/arc...)
SessionPageStatePersister uses Page object. AntiForgeryToken creates a dummy Page as a trick in order to use PageStatePersister. Looks like the dummy Page it creates is no good for the SessionPageStatePersister (i.e. it does not have the enablePageState set to true). Also because PageStatePersister is called in OnInit events, the Session is not available either.
So in order to resolve this issue you have to either:
- stop using SessionPageStatePersister or Teleriks compression thing (instead, you can use the DNN in-memory page cache - it eliminates the in-page VIEWSTATE by storing it in Cache)
- alternatively, comment out RegisterAjaxAntiForgery calls in DNN sources.
good luck