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  1. Minecraft: Java Edition
  2. MC-197225

Crash: java.util.concurrent.CompletionException: u: Exception generating new chunk


    • Community Consensus
    • Crash, Custom Worlds
    • Very Important

      The game crashes when a biome doesn't include the spawners arrays.


      "spawners": {} 

       No crash

      "spawners": {
          "monster": [],
          "creature": [],
          "ambient": [],
          "water_creature": [],
          "water_ambient": [],
          "misc": []

      Usually when certain fields are non optional, there is an error in the log and the biome doesn't load. However this is not the case here, and the game crashes.

      I have also experienced this freezing the game as seen in the screenshots

      How to reproduce

      1. Download the empty_spawners.zip data pack and install it in a world
      2. Teleport to the blip:test dimension
        execute in blip:test run tp @s ~ ~ ~ 

         The game crashes

      Time: 8/6/20 3:24 PM
      Description: Exception in server tick loop
      java.util.concurrent.CompletionException: u: Exception generating new chunk
      	at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:273)
      	at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:280)
      	at java.util.concurrent.CompletableFuture.uniCompose(CompletableFuture.java:961)
      	at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:926)
      	at java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:442)
      	at zu.b(SourceFile:58)
      	at zu$$Lambda$4225/119868154.run(Unknown Source)
      	at aob.e(SourceFile:94)
      	at aob.a(SourceFile:137)
      	at aob.run(SourceFile:105)
      	at java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1402)
      	at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:289)
      	at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1056)
      	at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1689)
      	at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)
      Caused by: u: Exception generating new chunk
      	at zs.a(SourceFile:579)
      	at zs$$Lambda$4261/699495355.apply(Unknown Source)
      	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
      	at zs.a(SourceFile:562)
      	at zs$$Lambda$4258/533721112.apply(Unknown Source)
      	at java.util.concurrent.CompletableFuture.uniCompose(CompletableFuture.java:952)
      	... 12 more
      Caused by: java.lang.NullPointerException
      	at bsd.a(SourceFile:460)
      	at chl.a(SourceFile:760)
      	at cfx.b(SourceFile:107)
      	at cfx$$Lambda$1772/194298413.doWork(Unknown Source)
      	at cfx$d.doWork(SourceFile:263)
      	at cfx.a(SourceFile:219)
      	at zs.a(SourceFile:568)
      	... 17 more

        1. crash-2020-08-06_15.24.44-server.txt
          3 kB
        2. empty_spawners.zip
          0.8 kB
        3. screenshot-1.png
          177 kB
        4. screenshot-2.png
          91 kB

            Unassigned Unassigned
            Misoloo [Helper] Misode
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