https://pastebin.com/fUfBBUbk

I'm having a similar issue on my server with the same version of Lootr and Minecraft (0.2.16.52 & 1.18.2)
I'll post logs if it happens again, but I went through the log OP posted and I found these common mods between my server and OP's: https://pastebin.com/ZdJMfKTh

I'm not sure what version of Forge OP is using, but I'm using Forge version 40.1.19 on my server.

It appears to be crashing when generating a treasure map.

What version of Minecraft and Lootr is this?

Apologies for the delay, I should have included the versions, here

MC 1.18.2
lootr-1.18.2-0.2.16.52
forge - 40.1.20
Server/Jelly mods
Radium Reforged (Lithium on Fabric) - 0.7.10.jar, could be causing issues?

This is an odd server deadlock that's happening when someone opens a chest.

Given that you're both using terralith and apparently having issues with exploration maps, could you test the following to ensure that it's not something Lootr is doing?

• Note the location of the chest
• Copy the world seed
• Disable lootr
• Create a new world using the exact same pack & settings with the current seed
• Open the chest without Lootr

If the crash doesn't occur, then it's definitely an issue with Lootr.

Unfortunately, without the world seed/identical set-up, there's no way for me to test it.

Conferring with FTBTeam/FTB-Modpack-Issues#809 seems to indicate that this is an issue with world generation of some description, rather than an issue with Lootr, unfortunately.

@Benjamboo @AstronomyGuy This appears to be an issue with the dummy structures from Terralith, which are used for their exploration maps, not being found.

Please see this comment on the Direwolf20 issue tracker for instructions on how to disable the map. There may be other mods involved (potentially Repurposed Structure's extension of the locate command, as well as Terrablender's biome changes) to actually cause the issue, but it doesn't appear to be specific to Lootr.