Systemctl --failed

systemctl --failed
  UNIT              LOAD   ACTIVE SUB    DESCRIPTION
● apache2.service   loaded failed failed The Apache HTTP Server
● [email protected] loaded failed failed Postfix Mail Transport Agent (instance -)

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.

2 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.

See also

• Systemd services: systemctl [status | is-active | start | daemon-reload | stop | mask | reload | restart | reboot | enable | disable | cat], systemctl list-units, systemctl list-timers, systemctl --failed, systemctl get-default, systemctl --help, .service, .timer, .socket, systemctl restart elasticsearch.service, systemctl status apt-daily, systemctl status oscapd