Microsoft JScript runtime error: 'Sys' is undefined 的解决方法

拖动一个ScriptMange，出现了“Microsoft JScript runtime error: 'Sys' is undefined”的错误的解决方案：

在 web.config-->system.web配置节添加
<httpHandlers> <remove verb="*" path="*.asmx"/>
            <add verb="*" path="*.asmx" validate="false" type="System.Web.Script.Services.ScriptHandlerFactory"/>
            <add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" validate="false"/>
        </httpHandlers>