On a few windows machine I go this error at about 25% but it did complete.
Hi Stephen
Did you run the uninstaller first?
Todd
yes I did - I found more servers had the error then didn’t
These are your old windows 2016 servers I would guess, otherwise you would use the auto upgrade scripts. Is that rigtht?
Todd
that is correct I think so
This has been around since Otto v1. We haven’t been able to get rid of it. It doesn’t happen on the majority of Windows servers. But some of them do get it from time to time. It is often a false negative, but sometimes you may have to manually start the server.
Todd
Thanks for adding your report. 
We’ll keep looking for the issue
Todd