The CheckMK agent is outdated. Version in ports: 2.3.0p16 Most recent version: 2.4.0p16 The port version also has the bug that it fails on Python plugins. Most recent version fixes this, e.g. for mk_postgres.py
^Triage: to which port does this Problem Report apply?
Sorry, missed that important info... net-mgmt/check_mk_agent Upstream: https://github.com/Checkmk/checkmk/blob/master/agents/check_mk_agent.freebsd