In certain scenarios, a failed Windows Vista upgrade to Windows 7 can throw the computer into a perpetual cycle of restarts, Microsoft informed. The Redmond company did not offer specific details on the causes of a Vista to Windows 7 upgrade failure, but it did offer a workaround for end users affected by this specific issue to put a stop to the continual reboots. The KB article Microsoft supplied for this issue was published after the RTM of Windows 7, and it indicates that the problem impacts all editions of Vista RTM, SP1 and SP2.

“When attempting to upgrade from Windows Vista to Windows 7 the upgrade attempt may fail with the message “This version of Windows could not be installed, Your previous version of Windows has been restored, and you can continue to use it." However, the next reboot of the machine will launch the upgrade process again only to fail with the same message,” the software giant informed.

The perpetual reboots are caused by the way the computer's Boot Configuration Database (BCD) store is modified in the Windows 7 upgrade process. While, the failed upgrade is capable of restoring the original Vista operating system before the jump to Windows 7 was attempted, it does not do the same with the BCD store.

“Windows Vista will have been restored on the computer but the Boot Configuration Database (BCD) store has not edited to restore Windows Vista as the default booting operating system,” Microsoft stated. “The computer will continue to boot to the Windows 7 Setup and then fail until the BCD database has been restored to its previous state.”

For the time being there is only a manual fix for the perpetual reboots. End users need to first of all select Windows Vista and not the default setup for Windows 7 when they are presented with the boot entry menu. Here are the additional steps that need to be taken in order to stop continual reboots for a failed Vista to Windows 7 upgrade process, according to Microsoft:

1. Insert the Windows Vista Media into the drive and exit the Windows Vista Setup when it’s launched
2. Click Start, All Programs, Accessories, and then right-click the Command Prompt icon, and then click Run as Administrator.
3. Type the following command at a command prompt and press ENTER
Drive:\boot\Bootsect.exe /NT60 All (Note: In this command, Drive is the drive where the Windows Vista installation media is located)
4. Restart your computer