Can’t really help you as I’m no freenas expert. I learned enough to get it set up and working then forgot most of it soon after.
Anyway just posting to say the same thing happened to me. Plex completely broken after a server update. Before that It broke and i fixed it by editing a file which has the wrong path in it because of a change in the way Plex works on freenas. Think the thread I followed was this one - https://forums.plex.tv/t/i-updated-to-plexmediaserver-1-15-0-659-9311f93fd-and-now-i-cant-access-server-setting/377180
I’ve since deleted my entire plex installation, upgraded freenas to 11.2 and created a new iocage plex which is now working but asking for updates it is not going to get. I’ve about given up on Plex on freenas and will set up a new server on windows soon, as it is a system i actually understand, and it will not be a crippled version of the server as a few features like premium music are not included in the freenas Plex server.
Good luck with your problem
