Windows 10 activation failed with error: 0x803F7001

I tried to activate Windows 10.  It failed with error 0x803F7001 and a description stating that the "Previous version was not activated". Following are the steps I performed to get to where I am now:

1. I have a laptop which had a single HDD and an OEM copy of Windows 8.1 pre-installed on it. I had no other drives.

2. In July 2015, I took advantage of the free Windows 10 upgrade and successfully upgraded from Windows 8.1 to Windows 10. I did not perform a clean install, just a regular upgrade from 8.1 to 10 on my HDD. I had no activation issues – everything worked like a charm.

3. Yesterday I physically removed my HDD from my laptop and inserted my SSD.

4. I performed a clean install on the SSD using the Windows 10 media creation tool.

Windows 10 will not activate. I am getting Error: 0x803F7001 with a description stating that the "previous version of Windows on this machine was not activated" which is false as described in my steps above.

I understood that the Windows activation servers blueprint your machine, taking the key from the BIOS and using that as a method of activating Windows 10. I also understood that in order for this to happen, you have to first upgrade to Windows 10 normally from Windows 7 / 8 (not clean install) after which you can perform a clean install. I have done just that. Then I swapped out my HDD (with the activated Windows 10 on it) for an SSD to perform a clean install. What did I do wrong?  How can I resolve this?

According to Microsoft:

Error code: 0x803f7001, 0x800704cF

This error means we didn’t find a valid Windows license for your PC.
[Basically, your hardware didn't match what's in Microsoft's database.]

You’ll need to use a valid product key to activate Windows. Your product key should be in the confirmation email you received after buying Windows, in the box Windows came in, included with the packaging your PC came in, or on the Certificate of Authenticity (COA) attached to the back or bottom of your PC.

If you’re activating Windows 10 (Version 1511 or higher), you can use a valid Windows 7, Windows 8, Windows 8.1, or Windows 10 product key.

If you have a valid product key, use it to activate Windows:

1. Select the Start button, then select Settings > Update & security > Activation.
2. Select Change product key, and then enter the 25-character product key.

From https://support.microsoft.com/en-au/help/10738/windows-activation-errors

Seeing that you had a valid copy of Windows 8.1, presumably you still have the licence sticker containing the product key? You can simply use that to activate Windows 10.

I recently reinstalled Windows 10 (with no hardware change) and yet was faced with the same error. Luckily I was able to dig up my Windows 7 product key and that activated Windows 10 for me successfully, using the steps above.