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  1. Minecraft: Java Edition
  2. MC-137300

ConcurrentModificationException thrown when upgrading world

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    Details

    • Confirmation Status:
      Confirmed

      Description

      The bug

      Converted worlds produce the error below in constantly when flying around, and chunks that should get loaded are not being loaded as seen in the screenshot.
      The example log took me ~30 seconds to get a few erors.

      [16:38:58] [Server thread/FATAL]: Error executing task
      java.util.concurrent.ExecutionException: java.util.ConcurrentModificationException
      	at java.util.concurrent.FutureTask.report(Unknown Source) ~[?:1.8.0_181]
      	at java.util.concurrent.FutureTask.get(Unknown Source) ~[?:1.8.0_181]
      	at k.a(SourceFile:200) [1.13.2-pre1.jar:?]
      	at net.minecraft.server.MinecraftServer.b(SourceFile:726) [1.13.2-pre1.jar:?]
      	at net.minecraft.server.MinecraftServer.a(SourceFile:681) [1.13.2-pre1.jar:?]
      	at dgh.a(SourceFile:131) [1.13.2-pre1.jar:?]
      	at net.minecraft.server.MinecraftServer.run(SourceFile:584) [1.13.2-pre1.jar:?]
      	at java.lang.Thread.run(Unknown Source) [?:1.8.0_181]
      Caused by: java.util.ConcurrentModificationException
      	at java.util.HashMap$HashIterator.nextNode(Unknown Source) ~[?:1.8.0_181]
      	at java.util.HashMap$EntryIterator.next(Unknown Source) ~[?:1.8.0_181]
      	at java.util.HashMap$EntryIterator.next(Unknown Source) ~[?:1.8.0_181]
      	at bnj.E(SourceFile:1162) ~[1.13.2-pre1.jar:?]
      	at java.util.concurrent.Executors$RunnableAdapter.call(Unknown Source) ~[?:1.8.0_181]
      	at java.util.concurrent.FutureTask.run(Unknown Source) ~[?:1.8.0_181]
      	at k.a(SourceFile:199) ~[1.13.2-pre1.jar:?]
      	... 5 more
      

      Code analysis

      Code analysis by [Mod] md_5 can be found in this comment.

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              • Assignee:
                fry [Mojang] Georgii Gavrichev
                Reporter:
                ichttt Tobias Hawk
              • Votes:
                14 Vote for this issue
                Watchers:
                7 Start watching this issue

                Dates

                • Created:
                  Updated:
                  Resolved:
                  CHK: