This error means that you have entered an incorrect or invalid username/password combination when trying to log in via the web VPN gateway or AnyConnect client. Make sure you are entering your single sign-on username/password and that you are typing it correctly. When connecting via the AnyConnect client make sure vpn.warwick.ac.uk is displayed in the 'Connect to:' box. If in doubt try changing your password and log in again.
Occasionally your password can get out of sync across the centrally managed systems which can prevent you from logging in. Try changing your password and log in again.