How to use Windows 8.1 RTM with 8.0 key?

Question

Is it possible to use the Windows 8.1 RTM Build from MSDN with an existing Windows 8.0 key?

I updated my laptop using one of our MSDN keys, and thought it would be possible to change back to the 8.0 key in the system control. But when I tried to change the key back to Windows 8.0, Windows rejected the key.

The Windows 8.0 key is an upgrade key, maybe this is relevant.

Solution

Is it possible to use the Windows 8.1 RTM Build from MSDN with an existing 8.0 Key?

It is indeed possible but you have to use one of the generic Windows 8.1 license keys below to install Windows 8.1 ( i.e. upgrade Windows 8.0 with the installation media ). The Windows 8.1 installer from the ISO does not accept Windows 8 keys. You need to install the system with a generic key and then enter your Windows 8 key after installing.

Core: 334NH-RXG76-64THK-C7CKG-D3VPT

Professional: XHQ8N-C3MCJ-RQXB6-WCHYG-C9WKB

_{Note to moderators: these are not usable Windows keys. They are embedded in Windows itself as a placeholder default key and do not let you activate.}

If you install the update through the Windows Store this isn't required. If you have Windows 8 Professional with Media Center you can also skip the step of having to basically downgrade to Windows 8 Professional then back to Windows 8.1 Professional With Media Center.

In order to do this I was force to use a generic license key which are stored on the Windows 8.1 installation media. Once the installation was done I was able to use slmgr.vbs to change my product key to a Windows 8.0 Upgrade license. I was running Windows 8 Professional so I did that by running the following two commands.

slmgr -cpky

slmgr -ipk XHQ8N-C3MCJ-RQXB6-WCHYG-C9WKB

Once you have performed this command you should restart your computer. Once the machine has been restarted you can attempt to activate Windows and when prompted provide your Windows 8 license key.

The quoted text above assumes you installed Windows 8.1 using a MSDN Windows 8.1 key, but the process still works, even if you installed Windows 8.1 with the generic key. All you do is remove the key using slmgr -cpky, restart the machine, and attempt to activate the installation and when prompted provide your actual Windows 8 license key.

Comments

[Lorenzo Von Matterhorn]

there seems to be a huge fuss about this issue around the internet. I can't come forth with a definitive answer, but surely someone more enlightened will for sure :)

[Cellcon]

@Ramhound - I have clarified it.

[Cellcon]

You wrote "but you have to use the MSDN Windows 8.1 key to install Windows 8.1" and that is just what I did. But I should have used the generic key for the Installation, because I cannot Change the MSDN Key to the generic one, right?

[Cellcon]

I now changed the Product Key to the generic one by using slmgr.vbs. Windows recognizes, it cannot be activated, but the Windows 8.0 key still does not work.

[Cellcon]

That's how it Looks like. Windows 8.0 Keys from MSDN are working (at least after using slmgr to set the generic key before trying the 8.0 one).

[Cellcon]

The generic keys are stored on the Installation media and - in my opinion - not secret at all. They are used by the installer, if you skip the key input (if possible) while Setup is running. I was able to Change the MSDN 8.1 key to a MSDN 8.0 Key. But I still want to use the Windows 8.0 Update Key.

[Cellcon]

I will try to get more information about this and will post my results.

[Cellcon]

Here is the solution: After installing Windows 8.1 with an 8.1 Key from MSDN, remove the key from the registry and then Change it to the generic one by using slmgr: slmgr -cpky slmgr -ipk <GenericKey> After that restart Windows completely by using shutdown -r -t 0. After the Computer ist back on, search for the "Activate Windows" option and provide the Windows 8.0 Update or OEM Key.

[Cellcon]

slmgr -cpky deletes the key from the registry - thats all.