This message appears, in especially that constillation (... as soon as host <UNIX> is active) appears if you did not assign a Host for the Object where it should run on
This issue can happen on
Jobs, Events, Filetransfers, all other agent based objects.
How to solve;
Assign this task to a specific host (might be adding it in Attributes section, or using PUT_ATT to add it via script in Pre Script
... not an entry like <UNIX> or <WINDOWS> but a specific agentname is shown in the errormessage? in that case this agent might either not be active, or not released for the specific client, restart the agent or ensure the agent is available for the client and run the job again
... This issue is shown for a non-agent-related task e.g. a Scriptobject or a Workflow in this case maybe the agent is used with e.g. a PREP_PROCESS_FILE or in a Condition within the Workflow, check conditions and script of the influenced task, maybe the agent you are relating to is not active, or you have a typo within the agentname you wrote in the script.