Update to 5.8.28 UniFi Controller for Unix
Update to 5.8.28 UniFi Controller for Unix

Note: UniFi Controller for Unix currently requires MongoDB 3.4.x or 3.5.x... will not work 3.6.x
Reference: https://community.ubnt.com/t5/UniFi-Updates-Blog/UniFi-SDN-Controller-5-8-28-Stable-has-been-released/ba-p/2449036
gozoinks/unifi-pfsense