Error 0x8004fc12 usually occurs with a clean install. This error means that windows cannot be activated. Since this is a generic activation error, it may also come up with other Microsoft programs such as Office 365, 2013 and 2016. The main reason for these errors are usually when the activation servers are busy, if this is the case then we need to wait until the servers are not busy for that; try re-activating a couple of hours later. Second most common cause for this to occur is if you are not on the Internet; this one is easy to check. Make sure your wirelessly or wired (connected) to the router and the internet’s up. When you are able to browse websites or use internet-related service, that means you are on the internet.
Lastly, the third most common reason for this to occur is if an update is pending which prevents a second request from your system to the activation servers.
If you have now ensured all the above points then we can proceed with the methods below to troubleshoot the issue further.
Check Your Firewall Settings
In the search box; type Firewall and choose Windows Firewall.
Turn the windows firewall off from here; then re-try activation. If you use a an anti-virus software and your firewall is managed by it; then make sure you turn the firewall off there as well. It can be done by hovering over the mouse to the anti-virus software icon and choosing the “disable” option by pulling down the menu (right-click). For AVG; it looks like this:
Lastly, if none of the above works then i would suggest you do a system file check