Another 0xC004c003 but think I know why but not how to fix The

I am getting the activation error 0xC004c003 invalid key like a lot of you too.

I upgraded a few windows 10 and they activated no problem but not this one.

I believe the problem is when I had windows 7 installed and activated I had to replace a hardware component.

When I had to reinstall Windows 7 to do this hardware change, Windows would not activate with my original key (OEM Version) so I had to go through the Microsoft phone activation and they give you new numbers to get it activated. It's not a new product key but the new numbers to get it activated. The phone verification thingie.

I believe microsoft is looking at my old product key and it is showing it is invalid as windows 7 did originally after the hardware change.

I looked up my product code when I reverted back to Windows 7 trying to fix this Windows 10 activation problem and it is still showing my original code even after the hardware change and re-activation with the new activation numbers.

If my Windows 7 was activated even after a hardware change I should still be eligible for the free Windows 10 upgrade!


Anyone know if this is my problem how can I get it fixed and Windows 10 activated?

Michaelrj9 said:

I am getting the activation error 0xC004c003 invalid key like a lot of you too.

I upgraded a few windows 10 and they activated no problem but not this one.

I believe the problem is when I had windows 7 installed and activated I had to replace a hardware component.

When I had to reinstall Windows 7 to do this hardware change, Windows would not activate with my original key (OEM Version) so I had to go through the Microsoft phone activation and they give you new numbers to get it activated. It's not a new product key but the new numbers to get it activated. The phone verification thingie.

I believe microsoft is looking at my old product key and it is showing it is invalid as windows 7 did originally after the hardware change.

I looked up my product code when I reverted back to Windows 7 trying to fix this Windows 10 activation problem and it is still showing my original code even after the hardware change and re-activation with the new activation numbers.

If my Windows 7 was activated even after a hardware change I should still be eligible for the free Windows 10 upgrade!


Anyone know if this is my problem how can I get it fixed and Windows 10 activated?

Same with me, replaced my HDD with SSD and called up microsoft on phone and the agent used a new code to activate windows 7.
i still have the code and also the key to my windows 7.