---- Minecraft Crash Report ----
// Ooh. Shiny.

Time: 28/05/18 18.00
Description: Exception in server tick loop

java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.UnsupportedOperationException
	at net.minecraft.server.MinecraftServer.g_(SourceFile:392)
	at dii.a(SourceFile:116)
	at dii.d(SourceFile:132)
	at net.minecraft.server.MinecraftServer.run(SourceFile:501)
	at java.lang.Thread.run(Thread.java:745)
Caused by: java.util.concurrent.ExecutionException: java.lang.UnsupportedOperationException
	at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2272)
	at net.minecraft.server.MinecraftServer.g_(SourceFile:390)
	... 4 more
Caused by: java.lang.UnsupportedOperationException
	at bpw.e(SourceFile:100)
	at sq.i(SourceFile:245)
	at sq.a(SourceFile:238)
	at bsi.a(SourceFile:29)
	at bsi.a(SourceFile:13)
	at bxf.a(SourceFile:26)
	at bxf.a(SourceFile:13)
	at bsl.a(SourceFile:27)
	at bby.a(SourceFile:515)
	at bpy.a(SourceFile:109)
	at sz.a(SourceFile:12)
	at sy.a(SourceFile:34)
	at bqc.a(SourceFile:87)
	at te.a(SourceFile:59)
	at te.a(SourceFile:23)
	at agg$a.a(SourceFile:131)
	at agg$a$$Lambda$1255/104214654.apply(Unknown Source)
	at java.util.concurrent.CompletableFuture$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:
---------------------------------------------------------------------------------------

-- System Details --
Details:
	Minecraft Version: 18w21b
	Operating System: Windows 10 (amd64) version 10.0
	Java Version: 1.8.0_25, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 79748488 bytes (76 MB) / 369098752 bytes (352 MB) up to 1073741824 bytes (1024 MB)
	JVM Flags: 8 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=16M
	Profiler Position: N/A (disabled)
	Player Count: 0 / 8; []
	Data Packs: vanilla
	Type: Integrated Server (map_client.txt)
	Is Modded: Probably not. Jar signature remains and both client + server brands are untouched.