How to upgrade Windows 7 Beta / RC to the Final RTM

I was suffering through taking my Windows 7 RC (7100) install up to the RTM edition.  Microsoft, if you can believe it, wants you to backup all your files and settings, wipe the thing, re-install, then replace the files and settings.  Uh…no.  So after an hour of pulling my hair out, I stubled across this comment by Roland Smeets and thought I would repost on the off chance someone else might be looking for this kind of info.

Credit to Roland Smeets as originally posted as a comment to http://technet.microsoft.com/en-us/library/dd446674(WS.10).aspx

Microsoft recommends Windows 7 beta or RC users to perform a clean or fresh installation of Windows 7 RTM, and uses Windows Easy Transfer to save and transfer user accounts, Windows settings, program settings, personal customizations and files from current installation to newly installed Windows 7 RTM system.The mechanism built into Windows 7 RTM to block and prevent upgrade from all pre-release versions of Windows 7 earlier than build 7233 for client edition, including Windows 7 Beta Build 7000 and Windows 7 RC Build 7100. For Windows Server 2008 R2, users can directly in-place upgrade from Windows Server 2008 R2 RC.

However, the hack similar to upgrade from Windows 7 Beta to RC can be used to hack the Windows 7 RTM installation DVD ISO to circumvent and bypass the blockage, in order not to be forced to exit gracefully from the upgrade.

1. Copy or download the Windows 7 RTM ISOto the computer that wants to perform the upgrade.
2. Mount the ISO image onto a virtual DVD drive and copy the whole content of the image to folder which can be located anywhere (on any partition or drive on the machine running the pre-release build, or external hard disk or USB/FireWire flash drive connected to the computer).

Alternatively, it’s possible to directly extract the content of the ISO to a desired folder using file extraction tool such as WinRAR.

1. Browse to the sources directory.
2. Open the file cversion.ini in a text editor such as Notepad.
3. Modify the MinClient build number to a value lower than the down-level build. For example, change 7233 to 7000.

Original content of cversion.ini: [HostBuild] MinClient=7233.0 MinServer=7100.0

Change it to: [HostBuild] MinClient=7000.0 MinServer=7100.0

1. Save the file in original place and original name. Double click on setup.exe from modified installation files to start Windows 7 installation, and choose Upgrade to in-place upgrade to latest RTM gold build of Windows 7. The version check will be skipped and bypassed.