Answer
It means the workflow engine has detected that running your workflow could trigger itself again in a loop, and it's stopping execution as a safety measure before that actually happens. The most common cause is a workflow that inserts a record (or triggers an event) that then causes the same workflow's own trigger condition to fire again — check whether any insert/update action inside your workflow touches the same table/entity (or triggers the same custom event) that originally started the workflow, since that's the pattern this specific safety check is designed to catch.