Upgrade a brand new Windows 11 Home to Pro (without leaving the out-of-box experience and without logging in with a non-corporate account) - Super User

1. Choose language, keyboard layout, device name etc.

2. Once you hit the login screen, press F10 to open CMD. Technically you can open CMD while it's installing Updates but I don't recommend this because it will restart without warning and might interrupt the following process.

3. Run slui.exe /upk. This is not always necessary but I suspect sometimes the Home license will be installed and needs to be removed first. Doesn't hurt to do anyway.

4. Run changepk.exe /ProductKey <Your product Key> It will say it failed but ignore it.

5. Restart

6. It's now Windows 11 Pro.

EX.

• Running changepk.exe /ProductKey VK7JG-NPHTM-C97JM-9MPGT-3V66T (Key for Windows 11 Pro) brought up the "Preparing for Upgrade" dialogue but then failed with Error Code 0x80070490

• I also tried slmgr.vbs /ipk VK7JG-NPHTM-C97JM-9MPGT-3V66T. This errored with 0xC004F069 and said to run SLUI to get full details. 

• I ran slui.exe 0x2a 0xC004F069 and it said 

• However, I then ran slui.exe /upk to uninstall the Product Key, and then tried changepk.exe again, after rebooting the OOBE was now for Windows 11 Pro and I could create a local user and domain join.