Sorry, seems some things here at git have changed and I didn't intend to link this to #572.

After updating, I get that error and the server shuts down. No crash log.
latest.log

FP-Latest.log

EDIT
Nice to see you're still developing this.

I think the main cause is this
[14:14:29] [Server thread/INFO] [net.minecraft.network.NetHandlerPlayServer]: trogarus lost connection: Timed out

you get somehow a timeout while joining the world.

I do, but it is not a network connection. After rolling hatchery back it stopped shutting down my local server. I’ve not timed out since

weird, I guess you should report that to hatchery too.

Upon further investigation, it seems to be some kind of interaction between FP and hatchery latest.

Looking at the mods I updated in the pack, rolling back FP didn't fix the issue. Rolling back hatchery did.

Hatchery version in question hatchery 1.12.2-2.2.2

Seems to be pointing to backpacks mod at this point. Have been running game a bit as I roll back and reset one mod at a time. Life is making the process slow 😁

take your time, please report back if you find the cause of this.

Still investigating. Going mod by mod in the update yesterday. Will report back. Making sure there are no other updated mods involved. Things were OK before I updated them.

Making it official. I've ran the game a while now with the Backpacks rolled back and seems no issues now.

backpacks+1.12.2+-+3.5.6.jar is the issue that seemed to be somehow causing the issue. Maybe some kind of weird mod interaction between the two? Don't know, but it seems rolling that mod back to previous version fixed things. Sorry to take so long to report back. If I run into anything related to this again, I'll post back, but seems, I'm probably not going to given the issue seems resolved.

Cool :) I will close this so feel free to reopen when it happens again.