Windows activation error 0xC004C008 appears when your product key has already been used on another device and exceeds the activation limit—meaning Microsoft’s server sees the key as already in use, so your PC can’t activate. This prevents Windows from becoming genuine and impacts personalization options.
To resolve it, follow these steps: restart your PC—and ensure only your current hardware is connected. Then run the Command Prompt as an administrator and execute:
slmgr.vbs /dlv
to view activation details and confirm the activation status. Next, enter:
slmgr.vbs /rearm
to reset the activation state. After restarting, go to Settings → System → Activation → Change product key, then re‑enter your valid Windows product key. If that doesn’t work, use:
slmgr.vbs /ipk <your‑product‑key>
slmgr.vbs /ato
to install and activate the key manually online.
If you still encounter error 0xC004C008, the key is likely already in use on another machine. You’ll need to purchase a new, unused Windows license or contact Microsoft Support to transfer your license if eligible. For a full, step‑by‑step walkthrough—including license transfer options—check out this detailed guide.