slmgr /ipk <your_KMS_client_key> slmgr /skms <your_KMS_server> slmgr /ato If using MAK:

After following these steps, run slmgr /ato again. If it still fails, the most likely remaining cause is — you may need to manually install an updated Microsoft Root Certificate Authority from a trusted 2024 source.

slmgr /ato If still fails with 0x80072f8f , try phone activation: