There is a trivial bug that caused by the vanilla Minecraft, that upon server try to convert animals from name to UUID, if the owner name is not in the Mojang database (because he changed his name), the server will jerk, if there are too many of them the server will even crash. I'm afraid that my wording may be terrible, but here is an example: One of my player "shuei_jing" tamed some wolves long ago, maybe a year and a half from now. The owner name was stored as string. Then he left the server with that area untouched for decades. Upon we upgrade to UUID system, he changed his name to "jie_jun" immediately, however his animals was not properly converted. Recently I did a dynmap render for my server (basically this will load every chunk once). My server almost crashed at a point when those animals are loaded. So my question is, is there any good ways to figure out how I could avoid those errors (kill'm all)?