“Invalid FORMATETC structure” error on control drag n drop

Today when I was developing Silverlight app using Telerik RadControls, there was an error “Invalid FORMATETC structure” prevented me to complete the drag n drop of RadControls to the XAML editor.

I didn’t have any idea what was caused it because I could still drag n drop the Button control to the XAML. I thought it was Telerik but it could be anything.

Then the fast way to get the answer was of course Google.

Oops there are may results when I searched invalid FORMATETC, that’s a good sign to get the answer. Yeah it’s not Telerik specific error but Visual Studio error. It’s caused by the reference of toolbox items were messed up.

The solution was simply resetting the toolbox items by right clicking the toolbox then choosing Reset Toolbox.

Be patience, it could take sometime to reload all toolbox items.