Hi, I tried to play on my serveur but all the time I have the same problem. I try to change maps and to delete mods but it is here, again.
java.lang.IllegalArgumentException: null
at net.minecraft.util.WeightedRandom.func_76273_a(SourceFile:18) ~[rs.class:?]
at net.minecraft.util.WeightedRandom.func_76271_a(SourceFile:37) ~[rs.class:?]
at net.minecraft.world.WorldEntitySpawner.func_77191_a(WorldEntitySpawner.java:266) ~[anb.class:?]
at net.minecraft.world.gen.ChunkGeneratorOverworld.func_185931_b(ChunkGeneratorOverworld.java:466) ~[aze.class:?]
at net.minecraft.world.chunk.Chunk.func_186034_a(Chunk.java:1019) ~[axw.class:?]
at net.minecraft.world.chunk.Chunk.func_186030_a(Chunk.java:999) ~[axw.class:?]
at net.minecraftforge.common.chunkio.ChunkIOProvider.syncCallback(ChunkIOProvider.java:110) ~[ChunkIOProvider.class:?]
at net.minecraftforge.common.chunkio.ChunkIOExecutor.tick(ChunkIOExecutor.java:150) ~[ChunkIOExecutor.class:?]
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:728) ~[MinecraftServer.class:?]
at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:397) ~[nz.class:?]
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:668) ~[MinecraftServer.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:526) [MinecraftServer.class:?]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_252]
[19:33:34] [Server thread/ERROR] [net.minecraft.server.MinecraftServer]: This crash report has been saved to: /home/minecraft/servers/mine148308/./crash-reports/crash-2020-11-06_19.33.34-server.txt
[19:33:34] [Server thread/INFO] [net.minecraft.server.MinecraftServer]: Stopping server
[19:33:34] [Server thread/INFO] [net.minecraft.server.MinecraftServer]: Saving players
[19:33:34] [Server thread/INFO] [net.minecraft.server.MinecraftServer]: Saving worlds
[19:33:34] [Server thread/INFO] [net.minecraft.server.MinecraftServer]: Saving chunks for level 'world'/overworld
[19:33:35] [Server thread/WARN] [mca]: Crash detected! Attempting to upload report...
[19:33:35] [Server thread/ERROR] [mca]: Failed to submit crash report. Non-OK response code returned: 301
[19:33:35] [Server thread/INFO] [FML]: Unloading dimension 0
[19:33:35] [Server thread/INFO] [FML]: The state engine was in incorrect state SERVER_STOPPING and forced into state SERVER_STOPPED. Errors may have been discarded.
[19:33:35] [Server Shutdown Thread/INFO] [net.minecraft.server.MinecraftServer]: Stopping server