Crash report when I try to go to this chunk. I've replaced the chunk from a working older copy but the error seems to still occur. Could it be because immersiverailroading stores data somewhere else? Any suggestions about fixing this without loosing the contents of the chunk.
crash-2021-10-12_19.05.17-server.txt

Optifine shouldn't be on the server

Removed Optifine, still crashing at the same point!
crash-2021-10-12_22.57.38-server.txt

Try upgrading to the latest IR release (1.9.1)

Now seems to work fine again, even with Optifine (couldn't do without it). Thanks for the help, still one of the best mods around.