Dravius

On start I want to say thath im form poland so my english can be not very good ;P The thing is that I create, a pack with mods (on minecraft 1.12.2) to play with my friend on LAN. For smth like 5 hours everything was great, no problems, everything was fine. When my friend decided to restart a server (he was host of server), and tried to enter to the world again game crashed. And this error appeared: The game crashed whilst exception in server tick loop Error: java.util.ConcurrentModificationException Kod zakończenia: -1 Can you help me with this problem, it was our series of minecraft hardocre, and this save is really imoportant for us. I dont know anything about java, I would ask for detailed instructions, what exactly should i do. Here is crash report: ---- Minecraft Crash Report ---- WARNING: coremods are present: llibrary (llibrary-core-1.0.11-1.12.2.jar) SSLoadingPlugin (SereneSeasons-1.12.2-1.2.18-universal.jar) LoadingPlugin (HardcoreDarkness-MC1.12.2-2.0.jar) LoadingPlugin (Reskillable-1.12.2-1.13.0.jar) LoadingPlugin (Bloodmoon-MC1.12.2-1.5.3.jar) Contact their authors BEFORE contacting forge // Why did you do that? Time: 1/19/21 12:58 AM Description: Exception in server tick loop java.util.ConcurrentModificationException at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429) at java.util.HashMap$ValueIterator.next(HashMap.java:1458) at net.minecraft.world.World.func_147448_a(World.java:1949) at net.minecraft.world.chunk.Chunk.func_76631_c(Chunk.java:856) at net.minecraftforge.common.chunkio.ChunkIOProvider.syncCallback(ChunkIOProvider.java:109) at net.minecraftforge.common.chunkio.ChunkIOExecutor.syncChunkLoad(ChunkIOExecutor.java:94) at net.minecraft.world.gen.ChunkProviderServer.loadChunk(ChunkProviderServer.java:118) at net.minecraft.world.gen.ChunkProviderServer.func_186028_c(ChunkProviderServer.java:89) at net.minecraft.world.gen.ChunkProviderServer.func_186025_d(ChunkProviderServer.java:135) at net.minecraft.server.MinecraftServer.func_71222_d(MinecraftServer.java:344) at net.minecraft.server.integrated.IntegratedServer.func_71247_a(IntegratedServer.java:210) at net.minecraft.server.integrated.IntegratedServer.func_71197_b(IntegratedServer.java:233) at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:486) at java.lang.Thread.run(Thread.java:745) I hope you can understand me, sorry for grammar.