If you have a workflow that is started on a mediapackage that has a workflow running, the POST to /workflow/dispatch fails with service unavailable.
The JobDispatcher claims that the server "is currently refusing to accept jobs of type START_WORKFLOW", but in fact the server here is refusing to start this specific job, not all jobs of that type.
The logging should be clearer as to the cause (e.g. "server SERVER refused to accept job JOBID of type JOBTYPE").
2017-04-12 22:06:45,258 | DEBUG | pool-14-thread-1 | (ServiceRegistryJpaImpl$JobDispatcher:3060) - Trying to dispatch job 58056012 of type 'org.opencastproject.workflow' to http://media.uct.ac.za
2017-04-12 22:06:45,283 | DEBUG | qtp1697235148-1491 | (AbstractJobProducerEndpoint:78) - Service org.opencastproject.workflow.impl.WorkflowServiceImpl@2bfd94d1 temporarily refused to accept job 58056012
2017-04-12 22:06:45,284 | DEBUG | pool-14-thread-1 | (ServiceRegistryJpaImpl$JobDispatcher:3069) - Service org.opencastproject.workflow@http://media.uct.ac.za is currently refusing to accept jobs of type START_WORKFLOW