Users who attempt to upgrade their computer to Microsoft Windows 8 may encounter a “Failure upgrading Windows. Preparing to retry” or a “Failure upgrading Windows. Reverting changes.” error. This is usually caused by third-party services running in the background. Try these steps to get things working.
1. Select Start, type msconfig, then press Enter.
2. Select the Services tab.
3. Check the Hide all Microsoft services check box.
4. Start unchecking any services you can. Anything that your computer doesn’t rely on for operation should be OK to uncheck. It’s really up to you to judge.
5. Select OK.
Now those services will not attempt to start during the Windows 8 upgrade, preventing the error. Once the upgrade is complete, you may have to re-enable or upgrade your software and services to a more compatible version.