Versions: BiomesOPlenty-1.11.2-6.1.0.2205-universal and BiomesOPlenty-1.11.2-6.1.0.2210-universal
Minecraft: 1.11.2
Forge: forge-1.11.2-13.20.0.2228
Other Mods: Dynmap-2.4-forge-1.11.2 -- cfm-4.1.2-mc1.11.2 -- RoguelikeDungeons-1.11.2-1.6.6

crash-2017-05-04_15.11.36-server.txt

I have a dedicated server. One player went into the nether the server started to slow down until it crashed. Everytime he enters the game again the server crashes. When other players enter the game the game runs fine until he enters the game again (he starts in the nether when he enters the game).

Update Forge

I can confirm that using the latest Forge 13.20.0.2294 fixed the problem. BUT I like to add that BiomesOPlenty-1.11.2-6.1.0.2205 and forge-1.11.2-13.20.0.2228 are both the latest recommended versions. It confuses when latest recommended versions don't work together.