While working through an integration of BlogEngine.Net into an existing web application I ran into a small issue with the Ajax controls I had implemented within the existing site. After the BE was migrated into the web application I noticed that when I viewed the page with the Ajax controls that rendering wasn't correct and that I started to get an error warning within the browser.
Digging deeper into the error and the rendering issue I found “Error: ‘Sys.Extended.UI’ is null or not an object”. Obviously it was some conflict with the controls from BE to the Ajax controls on the original site.
The solution turned out to be pretty easy, the controls used within BlogEngine.Net and the Ajax control toolkit used within my original web application were conflicting. The solution was to add the CombineScripts=”false” option.
Thanks to the following posts: