Volume Licensing Error Code 0xC004F042 shows up when KMS host cannot activate the client software. The full error message includes

The Software Protection Service determined that the Specified Key Management Service (KMS) cannot be used. 0xC004F042

When a KMS Client contacts the KMS host for activation, the host cannot activate the client computer. There can be multiple reasons for this:

1] Check if you are not using a KMS key to activate a client and not PUBLIC KMS.
2] Make sure the version of the client and the KMS server are matched.
3]Lastly, contact Microsoft Support to resolve if above two doesn't work.