While your warning is technically "valid", in response to the question asked, it's unhelpful. When someone explains they're having trouble doing a Windows upgrade (which Microsoft and Windows do allow admins to do, for good reason), "you shouldn't be doing that" just comes across as dismissive, especially before asking why they're doing an upgrade instead of a fresh install. I have been upgrading my Windows OSes my entire life, and, fortunately, aside from some small snags here and there, my upgrades have saved me countless hours of time. Like many people, time is something I never have enough of, so I value mine greatly. For the average configuration, despite the warnings about upgrading, I've found that Microsoft actually tends to do a pretty good job of making Windows upgrades work very well, and that seems to have gotten better with every release. In fact, I'm pretty sure (try not to gasp) that I upgraded my main PC all the way from Windows 95 to Windows 10 (even moving it to different hardware), and have several servers that have gone through 4 or 5 Windows Server version upgrades, and continue to work beautifully. Since an upgrade takes FAR less time than doing a fresh OS install, and reinstalling and reconfiguring every single component and app on that machine, those of us who don't have hours of time to do full re-installs on our workstations and/or servers have really good reasons to go the upgrade route, instead.