How to fix error 0xC004C008

About error 0xC004C008

The key has reached its activation limit or has been used on another device. Activate by phone:

1

Open Command Prompt as administrator and run the command below:
SLUI 4
2

Select the country and confirm.
3

Note down or take a photo of the displayed Installation ID.
4

Go to the official Microsoft activation portal (Chrome or Firefox).
https://aka.ms/aoh/
5

Choose the product: Windows 11 or Windows 10.
6

Enter the Installation ID and press Activate.
7

Immediately copy the Confirmation ID (it disappears quickly).
8

Enter the Confirmation ID in the open activation window.
9

The product is now activated and ready for use.

Even if the window provides a phone number, the call will redirect you to the same online portal. From 2025, activation is exclusively online.