Naturally, the Windows 8 Pro upgrade is for upgrading from an existing version of Windows. There’s even an Upgrade Assistant to verify that you’re ready to go. The upgrade software allows you to do a clean install, but unlike older versions of Windows it does not ask to see an installation disc of a previous version. Not until everything is running will the problem reveal itself: one cannot activate an upgrade from a clean install.
Watch your step!
If something goes wrong during upgrading requiring formatting the drive, or if later one loses a drive, the user may need to re-install their older copy of Windows first. The product key for an upgrade cannot be used to activate a clean install. The installation software never asks to see evidence of previous Windows installation, or warns that the key entered at the beginning cannot be used for a clean install. It’s a bit of a let-down to get through the entire installation only to be met with the message that you can’t continue using your OS unless you purchase another copy.
It appears that a number have discovered this problem (see comments at ghacks.net, “Windows 8 Upgrade: clean install possible?” and answers.microsoft) leaving some to wonder what happened to good user experience? This is Microsoft, remember, user experience isn’t a priority. According to Microsoft, “Why Can’t I Activate Windows,” the procedure is to first re-install an older Windows and then upgrade to Windows 8—or call technical support.
There’s another way to activate: edit the registry. The answer is the same as Windows 7. You can find it near the bottom of the article, at ghacks.net, “Windows 8 Upgrade: clean install possible?”
Why doesn’t the software warn the user about entering an upgrade product key before performing a clean install? Why doesn’t it ask for the product key—before or after installation—of your older version of Windows? Of course, that would require Microsoft to consider the user experience.
There’s a lot to like about Windows 8 including faster boot, better file management, and I like the new “start” menu.
Personal experience: The Windows 8 Preview installed and ran flawlessly for months, but the Windows 8 Pro upgrade lost itself on the first reboot, and I’ve encountered the same glitches after two installations (concerning stuck themes.) It seems strange that I had OS X up and running on a test machine (my “Hackintosh Test“) in less time with fewer problems.
Note: I’m a Windows .NET developer and formerly a Windows technical support consultant. For the last three years I’ve been using a Mac, but naturally I’m more familiar with the guts of Windows.