It seems that for some reason one of the VSExtensions assemblies has failed registering to the GAC. The best approach would be to run the installer, uninstall and reinstall the RadControls. The other workaround is to manually add the Telerik.VSX.Controls assembly (attached) to the GAC.
Here are the steps to do that:
- Extract the assembly in the attached archive to a preferred location
- Run the Visual Studio Command Prompt
- Run the following command: gacutil /i "[PATH_TO_THE_Telerik.VSX.Controls.dll]"
Let me know if that helped.
the Telerik team