System.Web.UI.IScriptControl Is Defined in an Assembly That Is Not Referenced Error Occurs

Environment

Product

Progress® Telerik® UI for ASP.NET AJAX

Description

When working with Telerik UI for ASP.NET AJAX, I get an error that System.Web.UI.IScriptControl is defined in an assembly that is not referenced and that I must add a reference to assembly System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35.

Error Message

The type 'System.Web.UI.IScriptControl' is defined in an assembly that is not referenced. You must add a reference to assembly 'System.Web.Extensions, Version=1.0.61025.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'

Cause

The possible cause for this error 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 Adding ASP.NET AJAX Configuration Elements to an Existing Web Site article.