I should have given you more details.
To continue from my previous comment:
- I uninstalled the MSI version with no issues.
- (It was installed by mistake and it took me a bit to realize I had installed the MSI version. Once I realized I couldn't use the MSI without other work, I decided I would just use the exe install version).
- I installed the exe version with no issues.
After all that, and after posting here, I tried to reproduce the problem, but I could not.
- I uninstalled the .exe version of 6.3.3.
- I installed the .exe version of 5.21.1.
- I installed the .exe version of 6.3.3 directly, while 5.21.1 was installed.
- previously, this is where I got the error 90:902
- this time I got no errors
- I uninstalled 6.3.3, installed 5.21.1, and installed 6.3.3 on top of 5.21.1 - again I had no issues.
- note - I kept my sessions in the hkcu registry and they worked without issue.
I don't know what the problem was. There was clearly something in my install of 5.21.1 that version 6.3.3 didn't like and couldn't upgrade. After uninstalling it though, 6.3.3 was able to install. But, after removing 6.3.3 and installing 5.21.1, installing 6.3.3 on top of 5.21.1 worked without issue.
Maybe there's something that gets set in the registry or somewhere else during normal use, and uninstalling the app cleared it.