https://support.microsoft.com/en-us/windows/using-the-windows-activation-troubleshooter-d717cdff-cf19-9770-7198-40119c2a696c

me too. have the problem after format. R240
- I sure the product key is correct (i record it before format 2499N-BCGX3-FHJKF-DH9QR-8B63W) 
- I install back the same OS(win2016), same name. 
- Install on same server, didnt change any hardware. maybe due to upgrade driver influence it? 
- The key able to match and insert to OS, but cant activate. (notification reason 0xC004f063)
- Everything seem ok, can detect the service tag in OS. 
what can i do? 

https://learn.microsoft.com/en-us/troubleshoot/windows-server/licensing-and-activation/0xc004f063-when-activating-oem-version

@ejn63​ able to show correct service tag on OS. and the key is correct. but still get the error 0xc004f063. 
after reformat, update driver only. nothing change on hw. same version of OS.