Microsoft JScript runtime error: AjaxControlToolkit requires ASP.NET Ajax 4.0 scripts. Ensure the correct version of the scripts are referenced. If you are using an ASP.NET ScriptManager, switch to the ToolkitScriptManager in AjaxControlToolkit.dll.

Solution: 1. Include assembly namespace in aspx page.

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit"

TagPrefix="asp" %>

2. If your control is right on your main page, chances are you have already done this.  But in my case the Ajax control was embedded in a user control, so I didn’t have it on the main page yet.

Then you can simply include the manager by changing the standard script manager

<asp:ScriptManager ID="scriptMaster" runat="server"></asp:ScriptManager>

to this:

<asp:ToolkitScriptManager ID="toolkitScriptMaster" runat="server">

</asp:ToolkitScriptManager>