When I try to launch or create a new world, my game output comes up with the following error messages:
Preparing spawn area: 6%
16:49:45 net.minecraft.server.MinecraftServer Encountered an unexpected exception
java.lang.RuntimeException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: Tried to access a block entity before it was created. b{x=161, y=70, z=1}
at net.minecraft.server.MinecraftServer.i_(SourceFile:395)
at cvl.a(SourceFile:115)
at cvl.d(SourceFile:131)
at net.minecraft.server.MinecraftServer.run(SourceFile:503)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.util.concurrent.ExecutionException: java.lang.RuntimeException: Tried to access a block entity before it was created. b{x=161, y=70, z=1}
at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2272)
at net.minecraft.server.MinecraftServer.i_(SourceFile:393)
... 4 more
Caused by: java.lang.RuntimeException: Tried to access a block entity before it was created. b{x=161, y=70, z=1}
at sf.f(SourceFile:181)
at bbs.a(SourceFile:230)
at bfj.d(SourceFile:158)
at axn.d(SourceFile:483)
at bfj.a(SourceFile:54)
at axn.e(SourceFile:492)
at bfj.b(SourceFile:58)
at bqk.b(SourceFile:57)
at bqk.a(SourceFile:124)
at bqn.a(SourceFile:63)
at sq.a(SourceFile:24)
at sm.a(SourceFile:34)
at bgq.a(SourceFile:89)
at sr.a(SourceFile:54)
at sr.a(SourceFile:23)
at zo$a.a(SourceFile:143)
at zo$a$$Lambda$878/114583575.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)
16:49:45 net.minecraft.server.MinecraftServer This crash report has been saved to: C:\Users\jerem\AppData\Roaming\.minecraft\crash-reports\crash-2018-02-13_16.49.45-server.txt
The following message also comes up:
Stopping server
16:49:45 net.minecraft.server.MinecraftServer Saving players
16:49:45 net.minecraft.server.MinecraftServer Saving worlds
16:49:45 net.minecraft.server.MinecraftServer Saving chunks for level 'Debug Mode'/overworld
16:49:45 net.minecraft.server.MinecraftServer Saving chunks for level 'Debug Mode'/the_nether
16:49:45 net.minecraft.server.MinecraftServer Saving chunks for level 'Debug Mode'/the_end
16:49:45 rz Couldn't stop taskManager
java.util.concurrent.ExecutionException: java.lang.RuntimeException: Tried to access a block entity before it was created. b{x=161, y=70, z=1}
at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:2237)
at zo.b(SourceFile:92)
at zq.a(SourceFile:25)
at rz.close(SourceFile:267)
at atm.close(SourceFile:2020)
at sa.close(SourceFile:1067)
at net.minecraft.server.MinecraftServer.j_(SourceFile:475)
at cvl.j_(SourceFile:311)
at net.minecraft.server.MinecraftServer.run(SourceFile:566)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.RuntimeException: Tried to access a block entity before it was created. b{x=161, y=70, z=1}
at sf.f(SourceFile:181)
at bbs.a(SourceFile:230)
at bfj.d(SourceFile:158)
at axn.d(SourceFile:483)
at bfj.a(SourceFile:54)
at axn.e(SourceFile:492)
at bfj.b(SourceFile:58)
at bqk.b(SourceFile:57)
at bqk.a(SourceFile:124)
at bqn.a(SourceFile:63)
at sq.a(SourceFile:24)
at sm.a(SourceFile:34)
at bgq.a(SourceFile:89)
at sr.a(SourceFile:54)
at sr.a(SourceFile:23)
at zo$a.a(SourceFile:143)
at zo$a$$Lambda$878/114583575.apply(Unknown Source)
at java.util.concurrent.CompletableFuture$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)
What does this mean? How can I fix it?
Linked issues
duplicates
Comments

Can you please attach the generated crash reports? Is this happening every time or only with a specific seed or world type?