The workaround -- which relies on editing the "cversion.ini" file in a downloaded copy of Windows 8 RTM -- tricks the installer into accepting upgrades from February's Windows 8 Customer Preview and May's Release Preview.

"Cversion.ini tells the installer the minimum build it can overwrite," said Cherry in an interview Tuesday. "By changing the version number there, it's allowed to overwrite the previews."

The cversion.ini file is only used to block previews of the final operating system; changing it does not affect the ability of Windows 8 RTM to upgrade Windows XP, Vista or Windows 7.

Cherry wasn't the only one who remembered that the when users wanted to upgrade from Windows 7 Release Candidate to the 2009 OS's final code.

Jason Fay gave the same advice as Cherry on , and said he was able to upgrade Windows 8 Release Preview to the RTM bits without problems.