Windows 10 Windows key error when trying to reinstall windows 10

[Eladzmr]

Hi all,
I am currently running windows 10.
I did an upgrade and clean install from windows 8.1.

Now I want to reinstall windows 10, but when I'm entering the windows 10 or 8.1 key I receive an invalid key.

What can I do in order to get a valid windows key to work with the new windows 10 installation?

Thanks.

 

[kemical]

Hi,
if you first upgraded then you do not need to input an activation key. When the upgrade set up files checks your current operating systems status regarding if it's activated and genuine it checks an 'activation database' something recently created by Microsoft. If the current operating system is activated and genuine then a windows 10 licence is issued and stored in the same location.
This means that when you clean install you do not need to input an activation key. May I ask which key you are using?