T420 Win7 Home fails to Windows Anytime Upgrade

I have a Lenovo T420 with Win7 Home Premium. When entering Win7 Ultimate key in Windows Anytime Upgrade, it gave "Windows Anytime Upgrade Was Not Successful" error.

Using "Windows 7 Upgrade Advisor" check my system, everything passes except Lenovo part. It says "More info from Lenovo" and has a link to Lenovo official site home page.

Can the community advise what Lenovo setting could cause my Windows upgrade fail? Thanks.

 

Have you tried this more than once? Do you have good internet connectivity before the upgrade starts?

 

I know very little about this stuff. I'll pass some info that I've read on to you.

Before taking any of my advise, back up all your data. Make sure you have a means of recovering your win7 OS, like lenovo recovery disks.

Are you given the option to do either an "upgrade" or a "custom install"?
I think you have to choose custom.
EDIT: oops I read the chart wrong. You have to choose custom if you are going from 32bit win7 home premium to 64bit win7 ultimate.

Official Windows 7 upgrade chart is ridiculous -- Engadget


I'm not sure if an anytime upgrade disk is any different from an upgrade disk. If not you may be able to use the anytime upgrade disk to do a clean (custom) install.

Instructions on how to do it by Paul Thurott. The double install method worked for me. Recommend you do it on a new harddrive so that if you have any trouble activating you can just put your old harddrive with win7 installed back in the thinkpad.
Clean Install Windows 7 with Upgrade Media

 

Thank you guys, especially that chart. I am just upgrading from Win7 Home Premium x64 to Win7 Ultimate. I figured out the upgrade process. Once entering the key and pass verification. I have to restart the PC instead of clicking upgrade button. That's it.