I got the same Problem: This Error occurs, before it is closing.
Same Message occurs when i want to Update via the Universal Installer.
It also makes no Difference, if i start the Updater as Admin or normal User.
Hope, there will be a fast Solution brought out by FSDT. The GSX is not working in the MSFS2020.
The GSX Button appears on the Toolbar, but clicking on it leads to nothing.
The Couatl Start for GSX on MSFS is up and running.