Opened again by Stephen Walther on May 8, 2013
I have a usercontrol inside a panel, that I would like to display, but I keep on receiving : Microsoft JScript runtime error: Unable to get value of the property 'UI': object is null or undefined
VS2010
Latest Nu-get Ajax Toolkit
.net 4.0
Comments: @Bill_H I use the Ajax Control Toolkit ToolkitScriptManager with the standard ASP.NET ScriptManagerProxy... It works perfectly on dozens of pages (for a big corporate site) so I'm not sure what your issue is. I had some issues a long time ago which meant I had to add EnableSecureHistoryState=false in the ToolkitScriptManager options... make sure EnableHistory=True as well.