I am setting up a new PC with Windows 10 Pro by deactivating an old PCs windows 10 Pro product key. I deactivated the old PC with the 2 commands "slmgr /upk" and "slmgr /cpky". I then proceeded to install windows 10 Pro onto the new PC specifying Windows 10 Pro as the version to install. It asked me for the product key from the old PC which i gave it and it accepted it. The system installed but I found out that Windows didn't activate. When I ran the activation troubleshooting wizard it told me that my product key was a Windows 10 Home key and was invalid for use with the Windows 10 Pro installation.

Does anyone know how this can happen and how to get the Windows 10 Pro installation to accept the old product key as a valid key?

  • Keys are also stored in the bios, which i suspect is where your problem lies, it is using the stored key instead of the one you entered. Did you try what Daniel suggested? – Moab Mar 28 '19 at 20:49
  • @Moab I read the link you posted and it suggests the problem is the product key is in the BIOS/UEFI. My PCs (both old & new) are old enough that niether of them have UEFI. I tried to find it in both BIOS's but couldn't find it in either one. The "new" PC seems to think that the product key I entered is the Windows 10 Home product key not a key in the BIOS (although it could be possible still). I took my key and re-registered it on the old PC & it activated without a problem & still says it is a windows 10 pro OS. Should I call M$? If so, do you know a # I can call? – user694665 Mar 28 '19 at 20:58

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