It could be that your Telerik WinForms VSExtensions are a bit outdated (we added the ClassLibrary project support in Q2 2011).
Can you try the following steps to update them and try the upgrade of your project again?
- Close all Visual Studio instances;
- Start a Windows Explorer and navigate to the [VS2010InstallDir]\Common7\IDE\Extensions\Telerik folder
- Delete all the Telerik WinControls VSExtensions folders (if any exist)
- Navigate to the %localappdata%\Microsoft\VisualStudio\10.0\Extensions\Telerik folder
- Delete the Telerik WinControls VSExtensions folders (if any exists)
- Download the latest version of the Telerik WinControls VSExtensions from the Online Gallery to a folder of your choice
- Start a Visual Studio 2010 Command Prompt
- Navigate to the folder you downloaded the Telerik WinControls VSExtensions
- Run the following command for the vsix package you downloaded:
vsixinstaller /a Telerik.WinControls.VSPackage.vsix
Let me know if that helps.
the Telerik teamSP1
of RadControls for WinForms is available for download
(see what's new