From what version of Windows were you attempting the WinX upgrade from? (IE: Win7/8/8.1). Also what is make/model of your computer you tried the WinX upgrade on? Upgrade compatibility can't be forced even using the Registry tweak you posted (I had seen this before) if your hardware is too old. If your Computer was built prior to 2006, and it did not have a dual-core processor or a single processor with dual-core, it's not going to work. Microsoft is not allowing upgrades on computers that came pre-loaded with earlier versions of Windows prior to Windows7 (IE: Vista & XP). Those computers much be clean installed with a ISO file created media downloaded from Microsoft app store. And, it doesn't work in all cases. 1 of my old Dell desktops built in 2007 worked this way, the other one built in 2008 did not. They both came pre-loaded with Vista. The Registry tweak you posted only works if your WinX can install via upgrade, which cannot happen with older computers (2008-2006).
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