When it comes to using pre-release versions of Windows 8, there is one major disadvantage: no full upgrade path. While performing a clean install is usually the most effective path, it is also the most tedious. Overriding your current version with the commercial version of Windows 8 means that you will need to re-install all your apps and redo browser settings along the way. Or does it?
Wait– but didn’t MS say you CAN upgrade Release Preview to Windows 8? Well yes, but keep in mind that it is only for personal settings. You will lose Metro/Modern apps and regular Windows applications with this route. The good news is that there is another option.
If you are willing to give it a try, it seems that there in fact a way to make Windows 8 beta versions fully upgradable while keeping existing apps and settings. Keep in mind that you do this at your own risk. So how does it work? Microsoft says it is impossible, but it requires a simple trick which makes the installer accept the full upgrade path.
The trick involves editing the cversion.ini file within the Windows 8 RTM download. This is the same method used in the past to upgrade pre-release Win7 builds over to the final code.
The file is found under sourcescversion.ini and can be opened easily in WordPad. All you need to do is change the two numbers that say “8508” over to “7100”. Save and exit. That’s all that is required. Pretty easy, huh?
How stable is it? Since I upgraded from Windows 7 to Windows 8, I can’t vouch for the safety and performance of this method. I would wager that the best answer is probably it depends. Regardless of what version you upgrading from, any time you elect to keeps apps and other settings there are unknown variables that can cause issues.
While the method highlighted above will technically work with Beta and Consumer Preview… using it with these really old versions might be asking for trouble.
For those with Release Preview, should you attempt the upgrade? That is entirely up to you. If you don’t mind the hassle of a clean install, it’s probably the best solution. If at least want to attempt an upgrade, make sure you back up important files in the event that it doesn’t work and a clean install becomes your only path.
Anyone attempted this method? Did you find success with it or not?[ source ]