Problem     :

在WebConfig添加了

<add name="Telerik_Web_UI_WebResource_axd" verb="*" preCondition="integratedMode" path="Telerik.Web.UI.WebResource.axd" type="Telerik.Web.UI.WebResource" />

页面依然报下面的错误，折腾了半天。最后在官网找到解决办法 如下

You receive the following error even if you had already added the handler.

~/Telerik.Web.UI.WebResource.axd‘ is missing in web.config. RadScriptManager requires a HttpHandler registration in web.config.

Cause:

The <handlers> or <httpHandlers> sections are placed under the <location> section and RadScriptManager cannot find them.

Resolution:

Set the EnableHandlerDetection="false" property of RadScriptManager.

引自：http://blog.csdn.net/silence20120807/article/details/9024033#comments