did you try opening 2018 alone not a saved file?
Did you run the installer “as administrator” ?
If not find it, right-click it and choose “Run as administrator” … then choose the repair option.
yes I tried all of that several times, helas without result
before I installed the 2019 update, SU 2018 was running smooth and fine.
Nothing happens trying to start up the app.
In order to be able to use SU I went back to 2016 version, which buggs me because of all library items being more recent