Please, help. I've spent hours troubleshooting with a friend. crashing when going back to base

[Rapisap]

Context

honestly i have no idea how to use this, but my i keep getting this in my server logs and server doesnt get a crash log or a real log on what happened so i dont know what to do, please, im tired, what does this mean. at first it was fine, until my friend went to go import his configs from the old instance of the modpack to the new one, and he ported the entire config file and thats when everything started going bad, though that doesnt really make much sense since it shouldnt be crashing the server only him. so we did a new fresh instance for him and whenever HE joined it crashed the entire server, so i teleported him to me like couple thousand blocks away cause thats where my base is, and he still crashes the entire server, ran the server one more time to make sure and it still crashed when HE joined, then i deleted his player data while still saving his items in a chest which i grabbed by the way so none of the items he had crashed me, then he logged on and it DIDNT crash, he grabbed his stuff and went back home in spectator mode, he went afk in a tent then went into the nether and then when coming out of the nether back to his base the server crashed again with the exact same message in the screenshots and the same disconnect with the logs. im at a loss here, im tired. i just want to play. please help me

Crash Report

https://mclo.gs/5eoTmCu and https://mclo.gs/EkwReRY

[berggggg]

Having this problem too. Sable seemingly does this super cool thing at random where it decides to just nuke your whole server as soon as one particular chunk is loaded, while also providing next to no helpful error information 🫠

[Shadowtrap1]

Same problem and I haven't found a good fix yet. At first I thought it was an update from apotheosis but so I set the mod versions to some older versions and it solved it. but now Im looking and cant figure out whats happening.