Upgrade from Windows 7 RC to Windows 7 Retail

If you did not already know this, you cannot perform an in-place upgrade from Windows 7 Beta or RC to Windows 7 Retail “out of the box.” Perhaps Microsoft just had a lapse of judgement on this, or perhaps its there way at getting back to all of us who refused to use Vista but jumped on the opportunity to use 7 before it was RTM. Either way, it really sucks for anyone who is using either version of Windows 7 for their production PC. Since the upgrade does not work natively, you are forced to reinstall the retail version from scratch – or are you?

Since I am running the Realease Candidate of Windows 7 and don’t much feel like reinstalling all of my applications then reconfiguring everything, I decided to figure out how to do an in-place upgrade. Here is how to do it:

1. Download the .iso image of Windows 7 Final
2. Extract the ISO to a folder
3. Browse to the “sources” directory.
4. Open cversion.ini in a text editor
5. Modify the MinClient build number to a value equal to or lower than the version you’re upgrading from. (If you’re running the RC, change the MinClient build number to 7100. If you’re running the beta, set it to 6900)
6. Save cversion.ini
7. Run setup.exe to start the upgrade.

NOTE: you will need a new key, as the beta and RC keys don’t work with the final version. You can choose to run the final version for 120 days in evaluation mode until you get a key.