java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0

What were you doing at the time of the crash?

This is from this morning.  In both known cases, the player was in a boat:

[10:46:40] [Server thread/ERROR]: Encountered an unexpected exception[10:46:40] [Server thread/ERROR]: Encountered an unexpected exceptionjava.util.concurrent.CompletionException: z: Feature placement at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:314) ~[?:?] at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:319) ~[?:?] at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1155) ~[?:?] at java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:478) ~[?:?] at abl.b(SourceFile:58) ~[server.jar:?] at ask.g(SourceFile:91) ~[server.jar:?] at ask.a(SourceFile:146) ~[server.jar:?] at ask.run(SourceFile:102) ~[server.jar:?] at java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1434) ~[?:?] at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:295) ~[?:?] at java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1016) ~[?:?] at java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1665) ~[?:?] at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1598) ~[?:?] at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183) ~[?:?]Caused by: z: Feature placement at abj.a(SourceFile:637) ~[server.jar:?] at com.mojang.datafixers.util.Either$Left.map(Either.java:38) ~[server.jar:?] at abj.a(SourceFile:619) ~[server.jar:?] at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1146) ~[?:?] ... 11 moreCaused by: java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0 at jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64) ~[?:?] at jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70) ~[?:?] at jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266) ~[?:?] at java.util.Objects.checkIndex(Objects.java:359) ~[?:?] at java.util.ArrayList.get(ArrayList.java:427) ~[?:?] at czb.a(SourceFile:52) ~[server.jar:?] at czb.a(SourceFile:47) ~[server.jar:?] at cyz.a(SourceFile:68) ~[server.jar:?] at cti.b(SourceFile:33) ~[server.jar:?] at cti.b(SourceFile:11) ~[server.jar:?] at cso.a(SourceFile:24) ~[server.jar:?] at ctb.a(SourceFile:63) ~[server.jar:?] at cth.a(SourceFile:38) ~[server.jar:?] at java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) ~[?:?] at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) ~[?:?] at cth.a(SourceFile:29) ~[server.jar:?] at ctb.a(SourceFile:63) ~[server.jar:?] at cth.a(SourceFile:38) ~[server.jar:?] at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) ~[?:?] at java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) ~[?:?] at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) ~[?:?] at java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:276) ~[?:?] at java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) ~[?:?] at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) ~[?:?] at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[?:?] at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) ~[?:?] at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) ~[?:?] at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:?] at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) ~[?:?] at cth.a(SourceFile:29) ~[server.jar:?] at ctb.a(SourceFile:63) ~[server.jar:?] at cth.a(SourceFile:38) ~[server.jar:?] at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) ~[?:?] at java.util.stream.IntPipeline$1$1.accept(IntPipeline.java:180) ~[?:?] at java.util.stream.Streams$RangeIntSpliterator.forEachRemaining(Streams.java:104) ~[?:?] at java.util.Spliterator$OfInt.forEachRemaining(Spliterator.java:699) ~[?:?] at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) ~[?:?] at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[?:?] at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) ~[?:?] at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) ~[?:?] at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:?] at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) ~[?:?] at cth.a(SourceFile:29) ~[server.jar:?] at ctb.a(SourceFile:63) ~[server.jar:?] at cob.a(SourceFile:288) ~[server.jar:?] at cod.c(SourceFile:115) ~[server.jar:?] at cod.a(SourceFile:256) ~[server.jar:?] at abj.a(SourceFile:625) ~[server.jar:?] at com.mojang.datafixers.util.Either$Left.map(Either.java:38) ~[server.jar:?] at abj.a(SourceFile:619) ~[server.jar:?] at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1146) ~[?:?] ... 11 more[10:46:40] [Server thread/ERROR]: This crash report has been saved to: /home ...

This is on rejoin:

---- Minecraft Crash Report -------- Minecraft Crash Report ----// Ouch. That hurt :(
Time: 9/20/21, 11:24 AMDescription: Feature placement
java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0 at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64) at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70) at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266) at java.base/java.util.Objects.checkIndex(Objects.java:359) at java.base/java.util.ArrayList.get(ArrayList.java:427) at czb.a(SourceFile:52) at czb.a(SourceFile:47) at cyz.a(SourceFile:68) at cti.b(SourceFile:33) at cti.b(SourceFile:11) at cso.a(SourceFile:24) at ctb.a(SourceFile:63) at cth.a(SourceFile:38) at java.base/java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) at cth.a(SourceFile:29) at ctb.a(SourceFile:63) at cth.a(SourceFile:38) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) at java.base/java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) at java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:276) at java.base/java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) at cth.a(SourceFile:29) at ctb.a(SourceFile:63) at cth.a(SourceFile:38) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) at java.base/java.util.stream.IntPipeline$1$1.accept(IntPipeline.java:180) at java.base/java.util.stream.Streams$RangeIntSpliterator.forEachRemaining(Streams.java:104) at java.base/java.util.Spliterator$OfInt.forEachRemaining(Spliterator.java:699) at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) at cth.a(SourceFile:29) at ctb.a(SourceFile:63) at cob.a(SourceFile:288) at cod.c(SourceFile:115) at cod.a(SourceFile:256) at abj.a(SourceFile:625) at com.mojang.datafixers.util.Either$Left.map(Either.java:38) at abj.a(SourceFile:619) at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1146) at java.base/java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:478) at abl.b(SourceFile:58) at ask.g(SourceFile:91) at ask.a(SourceFile:146) at ask.run(SourceFile:102) at java.base/java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1434) at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:295) at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1016) at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1665) at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1598) at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183)A detailed walkthrough of the error, its code path and all known details is as follows:---------------------------------------------------------------------------------------
-- Head --Thread: Server threadStacktrace: at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64) at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70) at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266) at java.base/java.util.Objects.checkIndex(Objects.java:359) at java.base/java.util.ArrayList.get(ArrayList.java:427) at czb.a(SourceFile:52) at czb.a(SourceFile:47) at cyz.a(SourceFile:68) at cti.b(SourceFile:33) at cti.b(SourceFile:11) at cso.a(SourceFile:24) at ctb.a(SourceFile:63) at cth.a(SourceFile:38) at java.base/java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) at cth.a(SourceFile:29) at ctb.a(SourceFile:63) at cth.a(SourceFile:38) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) at java.base/java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) at java.base/java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) at java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:276) at java.base/java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) at cth.a(SourceFile:29) at ctb.a(SourceFile:63) at cth.a(SourceFile:38) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) at java.base/java.util.stream.IntPipeline$1$1.accept(IntPipeline.java:180) at java.base/java.util.stream.Streams$RangeIntSpliterator.forEachRemaining(Streams.java:104) at java.base/java.util.Spliterator$OfInt.forEachRemaining(Spliterator.java:699) at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) at java.base/java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) at java.base/java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) at java.base/java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) at cth.a(SourceFile:29) at ctb.a(SourceFile:63)
-- Feature --Details: Description: ResourceKey[minecraft:worldgen/configured_feature / minecraft:flower_meadow]
-- Generation --Details: CenterX: -394 CenterZ: -384 Seed: 5250215393181259519Stacktrace: at cob.a(SourceFile:288) at cod.c(SourceFile:115) at cod.a(SourceFile:256)
-- Chunk to be generated --Details: Location: -394,-384 Position hash: -1644972474762 Generator: crh@1c354109Stacktrace: at abj.a(SourceFile:625) at com.mojang.datafixers.util.Either$Left.map(Either.java:38) at abj.a(SourceFile:619) at java.base/java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1146) at java.base/java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:478) at abl.b(SourceFile:58) at ask.g(SourceFile:91) at ask.a(SourceFile:146) at ask.run(SourceFile:102)
-- Affected level --Details: All players: 1 total; [abx['namemoved'/113, l='ServerLevel[edited]', x=-6149.68, y=62.07, z=-5970.01]] Chunk stats: 3702 Level dimension: minecraft:overworld Level spawn location: World: (16,109,128), Section: (at 0,13,0 in 1,6,8; chunk contains blocks 16,-64,128 to 31,319,143), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,-64,0 to 511,319,511) Level time: 7515327 game time, 8609254 day time Level name: iirc Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false Level weather: Rain time: 26393 (now: false), thunder time: 135943 (now: false) Known server brands: vanilla Level was modded: false Level storage version: 0x04ABD - AnvilStacktrace: at net.minecraft.server.MinecraftServer.b(SourceFile:896) at aax.b(SourceFile:335) at net.minecraft.server.MinecraftServer.a(SourceFile:833) at net.minecraft.server.MinecraftServer.x(SourceFile:690) at net.minecraft.server.MinecraftServer.a(SourceFile:274) at java.base/java.lang.Thread.run(Thread.java:831)
-- System Details --Details: Minecraft Version: 21w37a Minecraft Version ID: 21w37a Operating System: Linux (amd64) version 4.18.0-305.19.1.el8_4.x86_64 Java Version: 16.0.1, Oracle Corporation Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode, sharing), Oracle Corporation Memory: 1763692352 bytes (1681 MiB) / 10737418240 bytes (10240 MiB) up to 10737418240 bytes (10240 MiB) CPUs: 4 Processor Vendor: AuthenticAMD Processor Name: AMD Ryzen 7 3700X 8-Core Processor Identifier: AuthenticAMD Family 23 Model 113 Stepping 0 Microarchitecture: Zen 2 Frequency (GHz): -0.00 Number of physical packages: 1 Number of physical CPUs: 4 Number of logical CPUs: 4 Graphics card #0 name: Device Graphics card #0 vendor: Vendor (0x1234) Graphics card #0 VRAM (MB): 16.00 Graphics card #0 deviceId: 0x1111 Graphics card #0 versionInfo: unknown Virtual memory max (MB): 18212.11 Virtual memory used (MB): 17900.21 Swap memory total (MB): 6064.00 Swap memory used (MB): 0.25 JVM Flags: 11 total; -Xms10G -Xmx10G -XX:+UseG1GC -XX:+UnlockExperimentalVMOptions -XX:MaxGCPauseMillis=100 -XX:+DisableExplicitGC -XX:TargetSurvivorRatio=90 -XX:G1NewSizePercent=50 -XX:G1MaxNewSizePercent=80 -XX:G1MixedGCLiveThresholdPercent=50 -XX:+AlwaysPreTouch Player Count: 1 / 7; [abx['lkmsdfsdf'/113, l='ServerLevel[sdfsdfsdf]', x=-6149.68, y=62.07, z=-5970.01]] Data Packs: vanilla Is Modded: Unknown (can't tell) Type: Dedicated Server (map_server.txt)

I was able to duplicate this issue in single player mode:

seed: 6025187801934259743

teleport to x=-6149.68, y=62.07, z=-5970.01 and load some scenery, like the very large mountain.  

[00:10:22] [Render thread/INFO]: [CHAT] Seed: [6025187801934259743][00:10:22] [Render thread/INFO]: [CHAT] Seed: [6025187801934259743][00:10:29] [Server thread/INFO]: Saving and pausing game...[00:10:29] [Server thread/INFO]: Saving chunks for level 'ServerLevel[testseed]'/minecraft:overworld[00:10:31] [Server thread/INFO]: Saving chunks for level 'ServerLevel[testseed]'/minecraft:the_nether[00:10:31] [Server thread/INFO]: Saving chunks for level 'ServerLevel[testseed]'/minecraft:the_end[00:10:31] [Server thread/WARN]: Can't keep up! Is the server overloaded? Running 2523ms or 50 ticks behind[00:10:32] [Server thread/INFO]: Saving and pausing game...[00:10:32] [Server thread/INFO]: Saving chunks for level 'ServerLevel[testseed]'/minecraft:overworld[00:10:32] [Server thread/INFO]: Saving chunks for level 'ServerLevel[testseed]'/minecraft:the_nether[00:10:32] [Server thread/INFO]: Saving chunks for level 'ServerLevel[testseed]'/minecraft:the_end[00:11:32] [Server thread/INFO]: [wxczxc: Teleported wxczxc to -6148.500000, 62.000000, -5969.500000][00:11:32] [Render thread/INFO]: [CHAT] Teleported wxczxc to -6148.500000, 62.000000, -5969.500000[00:11:34] [Render thread/INFO]: Loaded 7 advancements[00:11:57] [Server thread/INFO]: [wxczxc: Set own game mode to Creative Mode][00:11:57] [Render thread/INFO]: [CHAT] Set own game mode to Creative Mode[00:12:02] [Worker-Main-5/WARN]: Worker-Main-5 diedjava.util.concurrent.CompletionException: z: Feature placement at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:314) ~[?:?] at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:319) ~[?:?] at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1155) ~[?:?] at java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:478) ~[?:?] at abl.b(SourceFile:58) ~[21w37a.jar:?] at ask.g(SourceFile:91) ~[21w37a.jar:?] at ask.a(SourceFile:146) ~[21w37a.jar:?] at ask.run(SourceFile:102) ~[21w37a.jar:?] at java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1434) ~[?:?] at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:295) ~[?:?] at java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1016) ~[?:?] at java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1665) ~[?:?] at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1598) ~[?:?] at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183) [?:?]Caused by: z: Feature placement at abj.a(SourceFile:637) ~[21w37a.jar:?] at com.mojang.datafixers.util.Either$Left.map(Either.java:38) ~[datafixerupper-4.0.26.jar:?] at abj.a(SourceFile:619) ~[21w37a.jar:?] at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1146) ~[?:?] ... 11 moreCaused by: java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0 at jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64) ~[?:?] at jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70) ~[?:?] at jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266) ~[?:?] at java.util.Objects.checkIndex(Objects.java:359) ~[?:?] at java.util.ArrayList.get(ArrayList.java:427) ~[?:?] at czb.a(SourceFile:52) ~[21w37a.jar:?] at czb.a(SourceFile:47) ~[21w37a.jar:?] at cyz.a(SourceFile:68) ~[21w37a.jar:?] at cti.b(SourceFile:33) ~[21w37a.jar:?] at cti.b(SourceFile:11) ~[21w37a.jar:?] at cso.a(SourceFile:24) ~[21w37a.jar:?] at ctb.a(SourceFile:63) ~[21w37a.jar:?] at cth.a(SourceFile:38) ~[21w37a.jar:?] at java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) ~[?:?] at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) ~[?:?] at cth.a(SourceFile:29) ~[21w37a.jar:?] at ctb.a(SourceFile:63) ~[21w37a.jar:?] at cth.a(SourceFile:38) ~[21w37a.jar:?] at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) ~[?:?] at java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) ~[?:?] at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) ~[?:?] at java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:276) ~[?:?] at java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) ~[?:?] at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) ~[?:?] at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[?:?] at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) ~[?:?] at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) ~[?:?] at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:?] at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) ~[?:?] at cth.a(SourceFile:29) ~[21w37a.jar:?] at ctb.a(SourceFile:63) ~[21w37a.jar:?] at cth.a(SourceFile:38) ~[21w37a.jar:?] at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) ~[?:?] at java.util.stream.IntPipeline$1$1.accept(IntPipeline.java:180) ~[?:?] at java.util.stream.Streams$RangeIntSpliterator.forEachRemaining(Streams.java:104) ~[?:?] at java.util.Spliterator$OfInt.forEachRemaining(Spliterator.java:699) ~[?:?] at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) ~[?:?] at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[?:?] at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) ~[?:?] at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) ~[?:?] at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:?] at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) ~[?:?] at cth.a(SourceFile:29) ~[21w37a.jar:?] at ctb.a(SourceFile:63) ~[21w37a.jar:?] at cob.a(SourceFile:288) ~[21w37a.jar:?] at cod.c(SourceFile:115) ~[21w37a.jar:?] at cod.a(SourceFile:256) ~[21w37a.jar:?] at abj.a(SourceFile:625) ~[21w37a.jar:?] at com.mojang.datafixers.util.Either$Left.map(Either.java:38) ~[datafixerupper-4.0.26.jar:?] at abj.a(SourceFile:619) ~[21w37a.jar:?] at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1146) ~[?:?] ... 11 more[00:12:02] [Worker-Main-9/WARN]: Worker-Main-9 diedjava.util.concurrent.CompletionException: z: Feature placement at java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:314) ~[?:?] at java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:319) ~[?:?] at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1155) ~[?:?] at java.util.concurrent.CompletableFuture$Completion.run(CompletableFuture.java:478) ~[?:?] at abl.b(SourceFile:58) ~[21w37a.jar:?] at ask.g(SourceFile:91) ~[21w37a.jar:?] at ask.a(SourceFile:146) ~[21w37a.jar:?] at ask.run(SourceFile:102) ~[21w37a.jar:?] at java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(ForkJoinTask.java:1434) ~[?:?] at java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:295) ~[?:?] at java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1016) ~[?:?] at java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1665) ~[?:?] at java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1598) ~[?:?] at java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:183) [?:?]Caused by: z: Feature placement at abj.a(SourceFile:637) ~[21w37a.jar:?] at com.mojang.datafixers.util.Either$Left.map(Either.java:38) ~[datafixerupper-4.0.26.jar:?] at abj.a(SourceFile:619) ~[21w37a.jar:?] at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1146) ~[?:?] ... 11 moreCaused by: java.lang.IndexOutOfBoundsException: Index 0 out of bounds for length 0 at jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64) ~[?:?] at jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70) ~[?:?] at jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266) ~[?:?] at java.util.Objects.checkIndex(Objects.java:359) ~[?:?] at java.util.ArrayList.get(ArrayList.java:427) ~[?:?] at czb.a(SourceFile:52) ~[21w37a.jar:?] at czb.a(SourceFile:47) ~[21w37a.jar:?] at cyz.a(SourceFile:68) ~[21w37a.jar:?] at cti.b(SourceFile:33) ~[21w37a.jar:?] at cti.b(SourceFile:11) ~[21w37a.jar:?] at cso.a(SourceFile:24) ~[21w37a.jar:?] at ctb.a(SourceFile:63) ~[21w37a.jar:?] at cth.a(SourceFile:38) ~[21w37a.jar:?] at java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) ~[?:?] at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) ~[?:?] at cth.a(SourceFile:29) ~[21w37a.jar:?] at ctb.a(SourceFile:63) ~[21w37a.jar:?] at cth.a(SourceFile:38) ~[21w37a.jar:?] at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) ~[?:?] at java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) ~[?:?] at java.util.stream.ReferencePipeline$Head.forEach(ReferencePipeline.java:762) ~[?:?] at java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:276) ~[?:?] at java.util.stream.Streams$StreamBuilderImpl.forEachRemaining(Streams.java:411) ~[?:?] at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) ~[?:?] at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[?:?] at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) ~[?:?] at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) ~[?:?] at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:?] at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) ~[?:?] at cth.a(SourceFile:29) ~[21w37a.jar:?] at ctb.a(SourceFile:63) ~[21w37a.jar:?] at cth.a(SourceFile:38) ~[21w37a.jar:?] at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:183) ~[?:?] at java.util.stream.IntPipeline$1$1.accept(IntPipeline.java:180) ~[?:?] at java.util.stream.Streams$RangeIntSpliterator.forEachRemaining(Streams.java:104) ~[?:?] at java.util.Spliterator$OfInt.forEachRemaining(Spliterator.java:699) ~[?:?] at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484) ~[?:?] at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) ~[?:?] at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:150) ~[?:?] at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:173) ~[?:?] at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) ~[?:?] at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:596) ~[?:?] at cth.a(SourceFile:29) ~[21w37a.jar:?] at ctb.a(SourceFile:63) ~[21w37a.jar:?] at cob.a(SourceFile:288) ~[21w37a.jar:?] at cod.c(SourceFile:115) ~[21w37a.jar:?] at cod.a(SourceFile:256) ~[21w37a.jar:?] at abj.a(SourceFile:625) ~[21w37a.jar:?] at com.mojang.datafixers.util.Either$Left.map(Either.java:38) ~[datafixerupper-4.0.26.jar:?] at abj.a(SourceFile:619) ~[21w37a.jar:?] at java.util.concurrent.CompletableFuture$UniCompose.tryFire(CompletableFuture.java:1146) ~[?:?] ... 11 more

I am unable to reproduce in 21w38a

Can you still reproduce this in 21w38a or later?

The underlying bug still exists in 21w38a code, and there is a duplicate issue with exact crash signature filed for that version.

Analysis: If for some reason class_6580#field_34712 (czk#h) is empty, list.get((int)(e * list.size())) in method_38445 (czk.a) will always be out-of-bounds (list.size() is 0, tries to get item 0, crash)

This ticket is a duplicate of MC-236755.

Thank you for your report!
We're tracking this issue in MC-236755, so this ticket is being resolved and linked as a duplicate.

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