关于 AjaxControlToolkit requires ASP.NET Ajax 4.0 scripts. 错误

错误: 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.

解决办法：

只要将：

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

更改为：

<asp:ToolkitScriptManager runat="server"></asp:ToolkitScriptManager>

当然在页面的头部，你有写

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %>

附 : ToolkitScriptManager VS ScriptManager