Our ASP.NET web forms project was updated from .NET 3.5 to .NET 4.5. This also meant we switched from Classic to Integrated pipeline mode for the App Pool. I began to see this error on pages that loaded the Telerik controls.
'~/Telerik.Web.UI.WebResource.axd' is missing in web.config. RadScriptManager requires a HttpHandler registration in web.config. Please, use
the control Smart Tag to add the handler automatically, or see the help for more information: Controls > RadScriptManager
After referencing the following webpages:
http://dotnetdawgs.com/post/Telerik-Web-UI-WebResource-axd-is-missing-in-webconfig.aspx
http://dotnet4europeanhosting.hostforlife.eu/post/European-ASPNET-Hosting-Amsterdam-How-to-resolve-7e-TelerikWebUIWebResourceaxd-is-missing-in-WebConfig.aspx
http://stackoverflow.com/questions/10889771/issue-with-telerik-web-ui-webresource-axd
http://stackoverflow.com/questions/7776087/when-i-run-asp-net-web-page-using-radgrid-telerik-control-on-server-side-it-gene?rq=1
I made the following changes...
I removed <httpHandlers> and <httpModules> from <system.web>
I removed the reference to the .NET 2 Telerik.Web.Design and Telerik.Web.UI DLLs, and added a reference to the .NET 4 DLLs.
I added <add name="Telerik.Web.UI.WebResource" path="Telerik.Web.UI.WebResource.axd" verb="*" type="Telerik.Web.UI.WebResource, Telerik.Web.UI" /> to the <system.webServer><handlers> section of web.config.
On my local workstation, this fixes the problem.
But, moving to our test web server, it still throws the same exception.
Test Server is confirmed running Windows Server 2008, IIS7, Integrated pipeline mode, .NET 4.5.
I've also tried leaving the <httpHandlers> in place, but that didn't work, either.
<httpHandlers>
<add path="Telerik.Web.UI.WebResource.axd" type="Telerik.Web.UI.WebResource" verb="*" validate="false" />
<add verb="*" path="Telerik.ReportViewer.axd" type="Telerik.ReportViewer.WebForms.HttpHandler, Telerik.ReportViewer.WebForms, Version=4.1.10.714, Culture=neutral, PublicKeyToken=a9d7983dfcc261be" />
</httpHandlers>