Error with Ajax Extensions for asp.net 4.0
ajax, asp.net, c#
Solution
Try to register the `AjaxToolkit` with
<ajaxToolkit:ToolkitScriptManager ID="ToolkitScriptManager1" runat="server">
</ajaxToolkit:ToolkitScriptManager>
Problem
I'm trying to get AJAX extensions working on an existing Web Forms Application. I've added the AjaxControlToolkit using Nuget. As a test I setup a page with a button and added a button confirmation extension. I'm getting this error: 0x800a138f - JavaScript runtime error: Unable to get property 'UI' of undefined or null reference On the following line in the dynamically created Javascript: ``` $create(Sys.Extended.UI.ConfirmButtonBehavior, {"ConfirmText":"Are ya totally sure?","id":"MainContent_Button1_ConfirmButtonExtender"}, null, null, $get("MainContent_Button1")); ``` I'm guessing that one of the libraries is the wrong version, but don't know how to go about figuring this out. I've tried to update packages using Nuget. Any ideas? Thanks!