Why I am getting this message 'Telerik is undefined'?

Question

I am developing an ASP.NET web-based application and I am using a Telerik tool with it. Everything works fine even in the production server in my company. Now, we have another server that we are using it for testing the web-based applications that we are developing. I copied my application from the production server to this testing server, but it did not work well on it. it opens the website but it shows me error message on the left bottom corner of the IE browser. It gave me the following error:

Telerik is undefined.

And because of this error, the application did not retrieve any data from the database on the Telerik tool controls.

I did not change anything in the application and I am using .NET 4 and it is installed in the both servers. Everything is the same but I don't know why I am getting this error. Do you any solution to this problem.

When I searched on the web, I found many resources and most of them talk about the web.config file and I tried most of these solutions without any luck. Why the application works in the first server and does not work in the second one?

The following snapshot shows you the error:

My web.config file is:

<configuration>
    <connectionStrings>
  <add connectionString="Data Source=localhost\sqlexpress;Initial Catalog=PMODServices;Integrated Security=True" name="PMODServicesConnectionString" providerName="System.Data.SqlClient" />
   </connectionStrings>
    <system.web>
         <customErrors mode="Off" />
        <compilation debug="true" targetFramework="4.0">
            <assemblies>
                <add assembly="System.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
                <add assembly="System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
                <add assembly="System.Speech, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
                <add assembly="System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
                <add assembly="System.Runtime.Serialization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
                <add assembly="System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
                <add assembly="System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
                <add assembly="System.Xml.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
                <add assembly="System.Data.DataSetExtensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
                <add assembly="Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
                <add assembly="Microsoft.ReportViewer.Common, Version=10.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
                <add assembly="Microsoft.Build.Framework, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
                <add assembly="System.Management, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
            <!--    <add assembly="office, Version=14.0.0.0, Culture=neutral, PublicKeyToken=71E9BCE111E9429C"/>  -->
                <add assembly="stdole, Version=7.0.3300.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" /></assemblies>
            <buildProviders>
                <add extension=".rdlc" type="Microsoft.Reporting.RdlBuildProvider, Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
            </buildProviders>
        </compilation>
        <httpHandlers>
            <!-- <add path="Telerik.Web.UI.WebResource.axd" verb="*" type="Telerik.Web.UI.WebResource" validate="false" />-->
            <add path="Telerik.Web.UI.WebResource.axd" verb="*" type="Telerik.Web.UI.WebResource, Telerik.Web.UI" validate="false" />
            <add path="ChartImage.axd" verb="*" type="Telerik.Web.UI.ChartHttpHandler" validate="false" />
            <add path="Telerik.Web.UI.SpellCheckHandler.axd" verb="*" type="Telerik.Web.UI.SpellCheckHandler" validate="false" />
            <add path="Telerik.Web.UI.DialogHandler.aspx" verb="*" type="Telerik.Web.UI.DialogHandler" validate="false" />
            <add path="Telerik.RadUploadProgressHandler.ashx" verb="*" type="Telerik.Web.UI.RadUploadProgressHandler" validate="false" />
            <add path="Reserved.ReportViewerWebControl.axd" verb="*" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" validate="false" />
        </httpHandlers>
        <authentication mode="Windows"/>

        <pages>
            <controls>
                <add tagPrefix="telerik" namespace="Telerik.Web.UI" assembly="Telerik.Web.UI" />
            </controls>
        </pages>
        <httpModules>
            <add name="RadUploadModule" type="Telerik.Web.UI.RadUploadHttpModule" />
            <add name="RadCompression" type="Telerik.Web.UI.RadCompression" />
        </httpModules>
    </system.web>

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

    <system.webServer>
        <validation validateIntegratedModeConfiguration="false" />
        <handlers>
            <remove name="ChartImage_axd" />
            <remove name="Telerik_Web_UI_SpellCheckHandler_axd" />
            <remove name="Telerik_Web_UI_DialogHandler_aspx" />
            <remove name="Telerik_RadUploadProgressHandler_ashx" />
            <remove name="Telerik_Web_UI_WebResource_axd" />
            <add name="Telerik_Web_UI_WebResource_axd" path="Telerik.Web.UI.WebResource.axd" type="Telerik.Web.UI.WebResource" verb="*" preCondition="integratedMode" />
            <add name="ChartImage_axd" path="ChartImage.axd" type="Telerik.Web.UI.ChartHttpHandler" verb="*" preCondition="integratedMode" />
            <add name="Telerik_Web_UI_SpellCheckHandler_axd" path="Telerik.Web.UI.SpellCheckHandler.axd" type="Telerik.Web.UI.SpellCheckHandler" verb="*" preCondition="integratedMode" />
            <add name="Telerik_Web_UI_DialogHandler_aspx" path="Telerik.Web.UI.DialogHandler.aspx" type="Telerik.Web.UI.DialogHandler" verb="*" preCondition="integratedMode" />
            <add name="Telerik_RadUploadProgressHandler_ashx" path="Telerik.RadUploadProgressHandler.ashx" type="Telerik.Web.UI.RadUploadProgressHandler" verb="*" preCondition="integratedMode" />
            <add name="ReportViewerWebControlHandler" preCondition="integratedMode" verb="*" path="Reserved.ReportViewerWebControl.axd" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" />
        </handlers>
        <modules runAllManagedModulesForAllRequests="true">
            <remove name="RadUploadModule" />
            <remove name="RadCompression" />
            <add name="RadUploadModule" type="Telerik.Web.UI.RadUploadHttpModule" preCondition="integratedMode" />
            <add name="RadCompression" type="Telerik.Web.UI.RadCompression" preCondition="integratedMode" />
        </modules>
    </system.webServer>
    <appSettings>
        <add key="Telerik.ScriptManager.TelerikCdn" value="Enabled" />
        <add key="Telerik.StyleSheetManager.TelerikCdn" value="Enabled" />
    </appSettings>
</configuration>

Answer 1

Remove this line of code from your web.config:

  <add key="Telerik.ScriptManager.TelerikCdn" value="Enabled" />

This is what worked for me after spending almost two days getting my page with a RadGrid to work.

Answer 2

I think it's about handler in web.config. Check that link.
http://www.telerik.com/help/aspnet-ajax/introduction-troubleshooting.html