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Sys Is Undefined Microsoft JScript Runtime Error Occurs

Environment

Product

Progress® Telerik® UI for ASP.NET AJAX

Description

When working with Telerik UI for ASP.NET AJAX, I get a Microsoft JScript runtime error that Sys is undefined.

Error Message

Microsoft JScript runtime error: 'Sys' is undefined

Cause

The possible cause for this issue is that you have added a Telerik UI for ASP.NET AJAX control but your application is not configured to use ASP.NET AJAX.

Solution

To solve this issue, follow the steps described in the Common reasons for the Sys is undefined error in ASP.NET Ajax applications blog post.

More troubleshooting steps are listed below:

Ensure that a page with asp:ScriptManager, an asp:UpdatePanel with a asp:Button inside operates as expected (i.e, performs AJAX requests)

Add location elements that allow access to all our handlers (http://docs.telerik.com/devtools/aspnet-ajax/general-information/web-config-settings-overview#mandatory-additions-to-the-webconfig) and to the ScriptResource.axd handler from the framework:

  <location path="Telerik.Web.UI.WebResource.axd">
    <system.web>
      <authorization>
        <allow users="*"/>
      </authorization>
    </system.web>
  </location>
  <location path="ScriptResource.axd">
    <system.web>
      <authorization>
        <allow users="*"/>
      </authorization>
    </system.web>
  </location>

Enable the Microsoft and Telerik CDN (http://docs.telerik.com/devtools/aspnet-ajax/controls/scriptmanager/cdn-support/overview):

<telerik:RadScriptManager ID="RadScriptManager1" runat="server" EnableCdn="true" CdnSettings-TelerikCdn="Enabled"></telerik:RadScriptManager>

You can find more information at: