Internal Server Error with httpHandlers section of web.config

Question

I have an asp.net website using the form controls from Telerik. It's just moved to a new server but I keep getting a 500 Internal Server Error.

Removing the httpHandlers section of the web.config makes server error go away, although then it complains if there is a Telerik control on the page. The whole config file is valid XML. Is there anything wrong with this code?

<httpHandlers>
    <add path="Telerik.Web.UI.WebResource.axd" verb="*" type="Telerik.Web.UI.WebResource, Telerik.Web.UI, Version=2008.2.826.20, Culture=neutral, PublicKeyToken=121fae78165ba3d4" validate="false"/>
</httpHandlers>

Answer 1

I see you mention it has just moved to a new server. Was this an IIS6 to IIS7+ migration?

IIS7 uses <system.webServer\handlers> instead of the IIS6 <httpHandlers> section. On top of this it will throw an error by default if you have the settings in the old section even if the new section is populated correctly.

Try this:

    <system.webServer>
        <validation validateIntegratedModeConfiguration="false" />
        <modules runAllManagedModulesForAllRequests="true" />
          <!-- modules here -->
        </modules>
        <handlers>
          <!-- modules here -->
          <add name="Telerik.Web.UI.WebResource" path="Telerik.Web.UI.WebResource.axd" verb="*" type="Telerik.Web.UI.WebResource, Telerik.Web.UI, Version=2008.2.826.20, Culture=neutral, PublicKeyToken=121fae78165ba3d4" />
        </handlers>
   </system.webServer>

The validateIntegratedModeConfiguration="false" will allow you to keep your httpHandlers section populated without throwing an error (useful if you are debugging on a cassini / iis6 server) and the entry in the <handlers> section will configure it for your IIS7 server.

The runAllManagedModulesForAllRequests="true" is not strictly required but you will probably find yourself needing it if you are new to configuring IIS7 :)