[Cura 4.2.1 does not start and makes 4.1 dead as well]

I had a similar situation yesterday with 4.2.0 installed.

So I uninstalled it, and went to 4.2.1.

It worked all day yesterday.

This morning, went to go back in to Cura, and 4.2.1 gets stuck with the "Updating configuration....".

Now after a reboot, it appears to be ok.

 

Look at the log file it creates during loading.

%AppData%\cura is the location of mine.

Check out stderr.log