1.12.2 modpack crash: Exception while updating neighbours

[jinxp0isn]

I am trying to make my own modpack, which is basicly an existing modpack with some added mods. I have managed to get that working after several days of trying, but when I imported my old world, from the old modpack, minecraft just crashes. When it crashes it's unknown which mod caused the crash, but this was in the crash report: "Exception while updating neighbours"

Is there a way to fix this?

https://pastebin.com/xDHNLtZr

[jinxp0isn]

Minecraft crashes right after the world is loaded in, my hotbar appears for a second before it crashes

[Luis_ST]

1.12 is no longer supported on this forum.
Please update to a modern version of Minecraft to receive support.