A freshly provisioned Unicorn Studio instance (107.8) was found by HOPS to have not started up correctly.
JIRA ran through its upgrade tasks and then failed with:
2011-10-03 16:04:00,648 main ERROR [user.provider.crowd.EmbeddedCrowdAccessProvider] Could not create group: jira-administrators com.atlassian.crowd.exception.runtime.OperationFailedException: The following URL does not specify a valid Crowd User Management REST service: http://highspectrum.jira.com/crowd/rest/usermanagement/1/group
A restart of JIRA did not improve the situation. I have attached full anonymised JIRA and Crowd logs showing the failed start-up.