---- Minecraft Crash Report ----
// Would you like a cupcake?

Time: 3/1/18 8:12 PM
Description: Exception generating new chunk

java.util.concurrent.ExecutionException: java.util.ConcurrentModificationException
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2237)
	at ry.c(SourceFile:129)
	at sf.a(SourceFile:84)
	at sg.c(SourceFile:143)
	at rz.k_(SourceFile:219)
	at net.minecraft.server.MinecraftServer.w(SourceFile:694)
	at net.minecraft.server.MinecraftServer.v(SourceFile:627)
	at cxk.v(SourceFile:155)
	at net.minecraft.server.MinecraftServer.run(SourceFile:532)
	at java.lang.Thread.run(Thread.java:745)
Caused by: java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(ArrayList.java:901)
	at java.util.ArrayList$Itr.next(ArrayList.java:851)
	at bqi.a(SourceFile:55)
	at bma$a.a(SourceFile:110)
	at bnd.a(SourceFile:87)
	at bpd.a(SourceFile:16)
	at bpd.a(SourceFile:13)
	at bjt.a(SourceFile:27)
	at aup.a(SourceFile:460)
	at bje.a(SourceFile:123)
	at sm.a(SourceFile:12)
	at sl.a(SourceFile:33)
	at bhq.a(SourceFile:85)
	at sr.a(SourceFile:54)
	at sr.a(SourceFile:23)
	at zn$a.a(SourceFile:143)
	at zn$a$$Lambda$990/951053208.apply(Unknown Source)
	at java.util.concurrent.CompletableFuture$AsyncApply.exec(CompletableFuture.java:501)
	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:902)
	at java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1689)
	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1644)
	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)


A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Thread: Server thread
Stacktrace:
	at ry.a(SourceFile:178)

-- Chunk to be generated --
Details:
	Location: 15,34
	Position hash: 146028888079
	Generator: bje@6b76f432
Stacktrace:
	at ry.a(SourceFile:178)
	at ry.c(SourceFile:132)
	at sf.a(SourceFile:84)
	at sg.c(SourceFile:143)
	at rz.k_(SourceFile:219)
	at net.minecraft.server.MinecraftServer.w(SourceFile:694)
	at net.minecraft.server.MinecraftServer.v(SourceFile:627)
	at cxk.v(SourceFile:155)
	at net.minecraft.server.MinecraftServer.run(SourceFile:532)
	at java.lang.Thread.run(Thread.java:745)

-- Affected level --
Details:
	Level name: Challenge V 13 Ruins
	All players: 1 total; [sb['RacinanteOpus'/726, l='Challenge V 13 Ruins', x=248.47, y=51.47, z=273.59]]
	Chunk stats: ServerChunkCache: 1456 Drop: 0
	Level seed: -1147604516778397343
	Level generator: ID 00 - default, ver 1. Features enabled: true
	Level generator options: 
	Level spawn location: World: (86,64,-188), Chunk: (at 6,4,4 in 5,-12; contains blocks 80,0,-192 to 95,255,-177), Region: (0,-1; contains chunks 0,-32 to 31,-1, blocks 0,0,-512 to 511,255,-1)
	Level time: 14136 game time, 14136 day time
	Level dimension: 0
	Level storage version: 0x04ABD - Anvil
	Level weather: Rain time: 19868 (now: false), thunder time: 114576 (now: false)
	Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: true

-- System Details --
Details:
	Minecraft Version: 18w09a
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.8.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 557146224 bytes (531 MB) / 1609113600 bytes (1534 MB) up to 8482586624 bytes (8089 MB)
	JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx8G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn1G
	Profiler Position: N/A (disabled)
	Player Count: 1 / 8; [sb['RacinanteOpus'/726, l='Challenge V 13 Ruins', x=248.47, y=51.47, z=273.59]]
	Data Packs: vanilla
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.