Telerik.Web.UI.WebResource Failed to Load

[Alex]

Telerik.Web.UI.WebResource is failing to load when I try and run my web site from my local IIS server. I can run it while debugging. I'm thinking it's an issue in my Web.config but after days of Googling I am out of ideas. 

<?xml version="1.0" encoding="UTF-8"?>
<!--
    Note: As an alternative to hand editing this file you can use the
    web admin tool to configure settings for your application. Use
    the Website->Asp.Net Configuration option in Visual Studio.
    A full list of settings and comments can be found in
    machine.config.comments usually located in
    \Windows\Microsoft.Net\Framework\v2.x\Config
-->
<configuration>
  <connectionStrings>

  </connectionStrings>
  <system.web>
    <!--
            Set compilation debug="true" to insert debugging
            symbols into the compiled page. Because this
            affects performance, set this value to true only
            during development.
        -->
    <compilation debug="true" targetFramework="4.0">
      <assemblies>
        <add assembly="System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <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.Drawing.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
      </assemblies>
    </compilation>
    <!--
            The <authentication> section enables configuration
            of the security authentication mode used by
            ASP.NET to identify an incoming user.
        -->
    <authentication mode="Forms" />
    <!--
            The <customErrors> section enables configuration
            of what to do if/when an unhandled error occurs
            during the execution of a request. Specifically,
            it enables developers to configure html error pages
            to be displayed in place of a error stack trace.

        <customErrors mode="RemoteOnly" defaultRedirect="GenericErrorPage.htm">
            <error statusCode="403" redirect="NoAccess.htm" />
            <error statusCode="404" redirect="FileNotFound.htm" />
        </customErrors>
        -->
    <pages theme="Theme" controlRenderingCompatibilityVersion="3.5" clientIDMode="AutoID">
      <controls>
        <add assembly="Telerik.Web.UI" namespace="Telerik.Web.UI" tagPrefix="telerik" />
      </controls>
    </pages>
    <httpHandlers>
      <add path="ChartImage.axd" verb="*" type="Telerik.Web.UI.ChartHttpHandler, Telerik.Web.UI, Version=2010.1.309.35, Culture=neutral, PublicKeyToken=121fae78165ba3d4" validate="false" />
      <add verb="GET,HEAD" path="ScriptResource.axd" type="System.Web.Handlers.ScriptResourceHandler, System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" validate="false" />
      <add path="Telerik.Web.UI.WebResource.axd" verb="*" type="Telerik.Web.UI.WebResource, Telerik.Web.UI" validate="false" />
    </httpHandlers>
    <httpModules>
      <add name="RadCompression" type="Telerik.Web.UI.RadCompression" />
      <add name="TelerikWebResource" type="Telerik.Web.UI.WebResource" />
    </httpModules>
  </system.web>
  <appSettings>
    <add key="DefaultActiveDirectoryServer" value="dc=foo,dc=com" />
  </appSettings>

  <!--
        The system.webServer section is required for running ASP.NET AJAX under Internet
        Information Services 7.0.  It is not necessary for previous version of IIS.
    -->
  <system.webServer>
    <validation validateIntegratedModeConfiguration="false" />
    <modules runAllManagedModulesForAllRequests="true">
      <add name="RadCompression" type="Telerik.Web.UI.RadCompression" />
      <add name="TelerikWebResource" type="Telerik.Web.UI.WebResource" />
    </modules>
    <handlers>
      <add name="ChartHandler" path="ChartImage.axd" verb="*" type="Telerik.Web.UI.ChartHttpHandler, Telerik.Web.UI" />
      <add name="Telerik_Web_UI_WebResource_axd" path="Telerik.Web.UI.WebResource.axd" type="Telerik.Web.UI.WebResource" verb="*" preCondition="integratedMode,runtimeVersionv2.0" />

  </handlers>
    <httpErrors errorMode="Detailed"/>
    <asp scriptErrorSentToBrowser="true"/>
  </system.webServer>
</configuration>

Any ideas what I'm missing here?

[Slav]

Hi Alex,

I noticed that you are using runtimeVersionv2.0 in the HTTP handler registration. Note that this is going to cause major issues, as when running in 4.0 the handler is bypassed, breaking functionality. Please remove runtimeVersionv2.0 and check whether the problem is resolved.

Regards,
Slav
Telerik

[Florin]

Thank you ! It is working! After 10 hours of searching and testing .. ...

[Rumen]

I am glad that you've managed to solve the issue, Florin.

For reference, the runtimeVersionv2.0 preCondition value is discussed in this KB article on the subject too: https://docs.telerik.com/devtools/aspnet-ajax/knowledge-base/using-controls-with-scriptmanager-login-page-error and this forum https://www.telerik.com/forums/telerik-web-ui-webresource-axd-and-web-config-once-and-for-all.