This blog post has been updated !!!

If you tried our Q1 2009 Beta you have probably noticed that there is a brand new assembly installed in your GAC - Telerik.Web.Design.dll. We decided to separate the design-time code from the web control implementation code. The reasons are many - better separation of concerns, less assembly references for the main assembly (Telerik.Web.UI.dll). We now have the freedom to extend the design time capabilities of RadControls for ASP.NET Ajax without bloating the main control assembly.

Why didn't we make it that way from the beginning? The only reason is that Visual Studio 2008 had a problem with loading GAC-ed design-time assemblies of control libraries deployed in the BIN folder of a web site. Strangely enough the problem didn't appear in Visual Studio 2005. The good news is that this bug has been fixed in Visual Studio 2008 SP1!

However if you for some reason cannot upgrade to Visual Studio 2008 SP1 you will face the following exception after upgrading to RadControls for ASP.NET Ajax Q1 2009:

Failed to create designer Telerik.Web.UI

Fortunately there are three ways to solve this problem (apart from the obvious upgrade to Visual Studio 2008 SP1):

  1. Bin-deploy the design-time assembly
    This solution would work only in case you have not installed RadControls for ASP.NET Ajax using the provided setup program. Assemblies installed by a setup program cannot be removed from GAC until the program is uninstalled. This approach is suitable when using only the dll-s from a zip (be that a hotfix or latest internal build).
    • Remove Telerik.Web.Design.dll from the GAC (this would fail if you have installed RadCotnrols for ASP.NET Ajax via the installer)
    • Copy Telerik.Web.Design.dll to your web site or application and make sure the dll is copied to the bin folder
    • Restart Visual Studio
  2. GAC-deploy the control library assembly
    • Add Telerik.Web.UI.dll in the GAC
    • Remove Telerik.Web.UI.dll from your bin folder
    • Make sure you have the following line in your web.config:
      <add assembly="Telerik.Web.UI, Version=2009.1.311.35, Culture=neutral, PublicKeyToken=121FAE78165BA3D4"/>
    • Restart Visual Studio
  3. Copy Telerik.Web.UI.dll to c:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\PublicAssemblies and restart Visual Studio.

I hope this helps.

About the Author

Atanas Korchev

 is Team Leader in Kendo UI Team

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