Note: You are currently viewing documentation for Moodle 1.9. Up-to-date documentation for the latest stable version is available here: error/mnet/hostnotconfiguredforsso.
This means that you have clicked on a link in the 'Network Servers' block to go to a remote host, but that your administrator has not ticked the appropriate boxes when setting up the network connection to that host.
In particular, the administrator has ticked the box to provide the 'SSO Identity Provider' service, but has not ticked the required dependency box to subscribe to the remote host's 'Service Provider' service.
This screenshot shows the issue:
Administrators: be very careful to read this page. When configuring SSO, you always need to check at least TWO boxes.