Microsoft JScript Runtime Error: ‘Sys’ is undefined solution

Want to learn AJAX system, unexpectedly just drag a ScriptMange, appeared “Microsoft JScript runtime error: ‘Sys’ is undefined” error, Google a, found that the original friends have also encountered a similar error, put the method post,

ajax.net1.0 official version
in web.config–> Add
< httpHandlers> < remove verb=”*” path=”*.asmx”/>
& lt; add verb=”*” path=”*.asmx” validate=”false” type=”System.Web.Script.Services.ScriptHandlerFactory”/>
& lt; Add the verb = “the GET and HEAD” path = “ScriptResource. Axd” type = “System. Web. Handlers. ScriptResourceHandler, System. Web. Extensions, Version = 1.0.61025.0, Culture = neutral, PublicKeyToken=31bf3856ad364e35” validate=”false”/>
& lt; /httpHandlers>

From:
http://www.cnblogs.com/zhonghua-sun/archive/2008/04/14/1152555.html