---- Minecraft Crash Report ----
// On the bright side, I bought you a teddy bear!

Time: 29.11.18 16:53
Description: Exception in server tick loop

java.util.concurrent.CompletionException: java.lang.AbstractMethodError: bxx$$Lambda$1056/2050277878.a(Lcom/mojang/datafixers/Dynamic;)Ljava/lang/Object;
	at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:273)
	at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:280)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1584)
	at ui$$Lambda$2095/122581069.accept(Unknown Source)
	at java.util.ArrayList.forEach(ArrayList.java:1249)
	at ui.e(SourceFile:369)
	at net.minecraft.server.MinecraftServer.q(SourceFile:641)
	at net.minecraft.server.MinecraftServer.p(SourceFile:625)
	at net.minecraft.server.MinecraftServer.a(SourceFile:422)
	at dog.a(SourceFile:91)
	at dog.d(SourceFile:107)
	at net.minecraft.server.MinecraftServer.run(SourceFile:562)
	at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.AbstractMethodError: bxx$$Lambda$1056/2050277878.a(Lcom/mojang/datafixers/Dynamic;)Ljava/lang/Object;
	at yg.a(SourceFile:18)
	at cat.<init>(SourceFile:44)
	at bvl$a.<init>(SourceFile:29)
	at bxc$$Lambda$994/1557594596.load(Unknown Source)
	at cax.a(SourceFile:86)
	at bqu.a(SourceFile:614)
	at bqu.a(SourceFile:229)
	at ui.d(SourceFile:439)
	at ui$$Lambda$2078/1319167476.get(Unknown Source)
	at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1582)
	... 10 more


A detailed walkthrough of the error, its code path and all known details is as follows:
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-- System Details --
Details:
	Minecraft Version: 18w48a
	Operating System: Windows 7 (amd64) version 6.1
	Java Version: 1.8.0_51, Oracle Corporation
	Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
	Memory: 525294872 bytes (500 MB) / 2013265920 bytes (1920 MB) up to 2147483648 bytes (2048 MB)
	JVM Flags: 9 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
	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.