Windows 10: Windows 10 Pro product key not accepted when activating a new replacement desktop

My old desktop has a valid Windows 10 Pro license bought in 2017 and still keep the product key. Today I have built a new desktop with more powerful processor and dismantle the old one. I also recycled all the drives, including the previous windows boot drive.
After the new desktop installation completed, I found out the product key cannot be used to activate the windows on my new desktop.

The pop-up message:

Unable to activate Windows
We can't activate Windows on this device because you don't have a valid digital license or product key. If you think you do have a valid license or key, select Troubleshoot below 0x803fa067


Have tried contacting support agent through online chat too many times and consistently got error before connecting.

Have tried finding phone number to call from the net and similarly unsuccessful.

Please help.

:)

 

New/Replacement Activation Key

You can purchase a Windows 10 Pro key then enter it yourself:

Step 1: Buy Windows 10 Home/Pro


Step 2:

Click Start > Settings > Update & security
> Activation > Change the product key then enter the new product key then click
Next to Activate





This can happen for a number of reasons:

• You copied a Windows 10 Pro off the Internet (usually a volume license - organization - key) and changed on a Windows 10 Home installation. Windows 10 Pro is not free.
  If this is what you did, you will need to reinstall the previous edition or version you were running. You inadvertently installed the wrong edition.
  • The copy of Windows 10 you download and upgrade from will correspond with the edition of Windows you have installed, if it does not, this is why you might be experiencing problems activating:

• Windows 7 Starter, Home Basic, Home Premium, Windows 8.0 Core, Windows 8.1 Core
  will install Windows 10 Home
  

• Windows 7 Professional, Windows 7 Ultimate, Windows 8.0 Pro, Windows 8.1 Pro
  will install Windows 10 Pro

To find out if you have the right edition installed:

Click Start > Settings > Update & security > Activation > Edition.

If the edition of Windows 10 installed does not correspond with the edition of Windows 7 or Windows 8 you were previously running, then you need to reinstall the right edition.

 

Win 10 Pro product key not accepted

I purchased a new laptop with Win 10 Home digital license. At the same time I purchased a Win 10 Pro update disk. When I try to change product key under Activation, the product key is not accepted. "The product key you entered didn't work".

 

Wont' accept product key of activation of window 10

have new computer with new windows 10 but can't activate will not accept product key