We found a 2021 version.  It installed, but uninstalled the working 2019 and won't run either.  Attached is the error message from 2021.  I'm now suggesting the user get QB tech on the phone.  This is an issue with QB. My gut says there's a random QB file that lingers and is preventing anything but 2019 to run.  And now 2019 is gone, so she's dead in the water. 

Thanks for your input.  It's all appreciated.

~Betsy