Raid nether

la console dit sur un serveur privé que il y a raid dans le nether 
mais on ne voit aucun raid ni monstre faisant parti des raids 
(je ne suis pas le créateur du serveur) 

erreur : 
[23:43:20] [Server thread/ERROR]: Error loading saved data: raids_nether java.lang.ArrayIndexOutOfBoundsException: null at java.lang.System.arraycopy(Native Method) ~[?:1.8.0_72] at java.io.PushbackInputStream.unread(PushbackInputStream.java:235) ~[?:1.8.0_72] at cnz.a(SourceFile:104) ~[server.jar:?] at cnz.a(SourceFile:80) ~[server.jar:?] at cnz.b(SourceFile:61) [server.jar:?] at cnz.a(SourceFile:42) [server.jar:?] at vg.<init>(SourceFile:176) [server.jar:?] at uy.<init>(SourceFile:15) [server.jar:?] at net.minecraft.server.MinecraftServer.a(SourceFile:416) [server.jar:?] at net.minecraft.server.MinecraftServer.a(SourceFile:370) [server.jar:?] at ug.d(SourceFile:218) [server.jar:?] at net.minecraft.server.MinecraftServer.run(SourceFile:605) [server.jar:?] at java.lang.Thread.run(Thread.java:745) [?:1.8.0_72]