TASM ruleset activation error

Problem :

We try to activate a ruleset and get this error.
Copying to WORKING rulesets gives same error.
Importing .xml file from what we exported prior to the cutover results in another error:
Cannot import Full TASM Ruleset to a Restricted System.
Red triangle says Internal Error: Contact the dministrator.

Cause :

Hosts file was pointing at the decommissioned Teradata system, not the NPARCed system.

Solution :

Customer modified /etc/hosts to use the correct IP address for the new system.