you have some work to do to salvage your FTB servers. (multiple?)
i can see from your posted log that the server is starting normally but because you still use the old saved world files things are not loading/working properly. my feeling is it has to do with the original issue Sir hexparrot solved for you namely, using root.
again, my own feeling but by using root a whole cascading unforseen series of events take place and unintended results occur. every time. take it from me, Hahaha, i know all about it so welcome to the club.
no worries, now we know. MineOS used as intended works great. it even works great used as unintended. it was never intended to be used as root so the headline “Web UI not running server properly” is missleading. trash in trash out at best is the rule.
anyway, what i mean is this: for whatever reason your old “world” file was built with mods like tinkers constuct. open computers, storage drawers and the like. but now, as the server loads the world those mods are not loading properly. as such the server deals with items made with the mods by posting warnings and dealing with them as it can by skipping them or whatever.
finally it looks like it errors out and crashes but i’m not sure. whatever.
it seems to me the original error of building the servers as root has had its residual effects here.
now you will learn what the back ups and archives are for, lol.
make them, move them. delete your servers. rebuild your servers as intended (mc as user, not root) import your back ups and get them up and working properly. (i would use the node js version, just a thought.)
when all the mods load and are working the old world files should load and work fine as well.
help is around here someplace but it is a big sports weekend in the usa.
EDIT: forgot to mention, you may have to end up rebuilding your servers and importing only the world folders because the saved archive as is may still crash. you simply get the new FTB servers up and stable with all the mods running, shut down, place your old world files into the new world folder and see what happens when you start the server.