We’ve been using the Telerik ASP.NET Ajax control suite for quite a while now to speed products to market with rich Ajax functionality. We’ve also been forced to reinstall operating systems and development software many times over the years, and the Telerik controls have reinstalled themselves with varying degrees of success.
The most nagging issue we’ve run into is the controls not installing themselves correctly within the Visual Studio toolbar, a problem which seems to have been corrected in the build we just installed (January 2010). However, the controls still failed during design time throwing an error that we’ve seen many times during many past installs:
“Failed to create designer ‘Telerik.Web.UI.RadTreeView,…”
It’s not just the tree view, it’s any control that needs design-time support from their codebase. The solution to this problem is moving the compiled DLL into the Visual Studio folder. We found the answer in this obscure article on their site which we tracked down through a forum post.
The solution is as follows:
Copy Telerik.Web.UI.dll to c:\Program Files\Microsoft Visual Studio 9.0\Common7\IDE\PublicAssemblies and restart Visual Studio.
That made our Telerik installs happy. Please note that you’ll need to do this manually as you upgrade your component suites.