I get this every time I update another assembly. I save my initial config file, go to my assembly, and try to load the fresh version. This error comes up every time, and THEN when I try again it works.
1/2 the time, the popup is also not being loaded to the front of my window, but behind Fusion so only after 30 seconds do I realize and then when ALT-Tabbing am I able to see it.
Please click "Accept Solution" if what I wrote solved your issue!