Windows 10: Unable to change product key from home to pro

I have purchased a license for Windows 10 pro. But currently my PC is running Windows 10 Home. I go to the Settings trying to change a product key but the box is filled with the old product key and the system doesn’t allow me to change it.

:)

 

Why was I not asked for a product key when upgrading to Win 10?

According to your spec you have Win 10 Pro, but perhaps that doesn't reflect your PC.

You haven't stated which edition of Win 10 you have on this machine, nor what your Win 10 key is for.

For example, if you already have Win 10 Pro and your key is Win 10 Home, that would be a retrograde step.

For interest only:
Change Product Key in Windows 10

More on product key if you search this list or look at 'Related Tutorials' in the above.
Windows 10 Tutorial Index

 

Home to Pro Key not working

https://support.microsoft.com/en-us/...ng-home-to-pro

Upgrade using a Windows 10 Pro product key To upgrade from Windows 10 Home if you have a Windows 10 product key:

• Select the Start button, then select Settings > Update & security > Activation.
• Select Change product key, and then enter the 25-character Windows 10 Pro product key.
• Select Next to start the upgrade to Windows 10 Pro.

 

Unable to use the option Change Product Key

II have a product key for windows pro. When I go into Settings to change product key from Home to PRO, It asks for Product Key which is filled in with X's and 0's. When I try to enter my product key it will not let me enter my key. As soon as I try
to enter the first Digit, it does not accept it and immediately goes to message saying I entered a wrong product key. How do I correct this problem. I installed the Pro edition but it will not activate it because it says I do not have a product key. Can
anyone help me??

***Modified title from: Change Product Key***