Hi there
This is very strange.
This tool requires UE 4.23 at least, are you using a specific version of the engine, is it the epic launcher version? Or a compiled version from GitHub or modified engine?
If you are able to go into your ProjectFolder\Saved\Logs and open the latest modified txt file in there, if you look around the end of the file there should be more details about the error, see if there is anything there
Or you can copy paste the end of the file here, or attach it so i can take a look?
After googling that error it looks like some people solved that problem by deleting the /intermediate /saved and /build folders, you could give that a try