This 2020 blog post tells you how to fix the Setup Initialization Error 432 on Windows 10.
Warning: You make any changes to your Windows 10 PC at your risk.
I wanted to install a very old application and saw the error message:
“Setup Initialization Error
Setup has detected that uninstallShield is in use. Please close uninstallShield and restart setup.
So I looked in task manager for another installation, but couldn’t see anything. What resolved the problem was renaming IsUninst.exe in c:\Windows\ to IsUninstOLD.exe.
Then when I ran the setup application again, I didn’t see the error message and I noticed the IsUninst.exe application reappear, next to the renamed one.
I don’t usually like making modifications to the Windows directory. In my case, I was running a patch for an application from 2000, long before Windows 10 was released.