First off, I have little experience with DNN.  Recently I upgraded a working DNN6 site (that I “inherited”) to DNN9.  The upgrade ran fine and everything looked fine except for pages with a “LeftMenu” control.  On pages with a LeftMenu control, the other controls (e.g. textboxes) were displaying fine but they were not returning newly entered text to the codebehind.

I am using IE11 and I noticed these pages work in Chrome and Firefox.  If I run with the debugger in IE and set the mode to IE 10 the page also works.

These pages are setup to use a page theme, “DarkKnight - Double-Menu”.  I have other pages that work in IE11 that use a page theme of “DarkKnight – WidePage”.  These pages using “WidePage” don’t include “LeftMenu” and work fine under IE11.

When I load a page with LeftMenu in the debugger I get an exception:

            SCRIPT438: Object doesn't support property or method 'attachEvent' File: Telerik.Web.UI.WebResource.axd, Line: 5465, Column: 7

The script is in a method:  b.RadPanelItem.prototype._attachEventsToTheHeaderElement. 

The script is trying to call: e.attachEvent("onclick", this._onExpandHandleClick);

Here, “e” is an HTMLSpanElement.  I know that attachEvent is not supported in IE11; addEventListener should be used.  So why is this calling attachEvent?

Is there a bug in the script in Telerik.Web.UI.WebResource.axd or is there some old file from DNN6 that is causing this error.  Something else?  I am stumped.