[BUG] Cosmos Library throwing IndexOutOfBounds Exception on ArrayList.add()

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#48,056 opened on Feb 20, 2026 1 comment 0 reactions 1 assignee Claimed by @kushagraThapar View on GitHub

Cosmos customer-reported needs-team-attention question

Dominant language: Java
Stars: 2.6k
Forks: 2.2k
Avg merge: 2d 7h
Merged PRs (30d): 211

Description

**Describe the bug**
When calling `cosmosTemplate.runPaginationQuery()`, we intermittently run into an ArrayIndexOutOfBounds exception.

***Exception or Stack Trace***
```
java.lang.ArrayIndexOutOfBoundsException: Index 1 out of bounds for length 0

at java.base/java.util.ArrayList.add(ArrayList.java:484)

at java.base/java.util.ArrayList.add(ArrayList.java:496)

at com.azure.cosmos.implementation.query.Fetcher.lambda$nextPage$6(Fetcher.java:225)

at reactor.core.publisher.FluxDoFinally$DoFinallySubscriber.runFinally(FluxDoFinally.java:146)

at reactor.core.publisher.FluxDoFinally$DoFinallySubscriber.cancel(FluxDoFinally.java:135)

at reactor.core.publisher.Operators.set(Operators.java:1249)

at reactor.core.publisher.FluxMergeSequential$MergeSequentialInner.cancel(FluxMergeSequential.java:608)

at reactor.core.publisher.FluxMergeSequential$MergeSequentialMain.onNext(FluxMergeSequential.java:240)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.FluxGenerate$GenerateSubscription.next(FluxGenerate.java:178)

at com.azure.cosmos.implementation.query.Paginator.lambda$getPaginatedQueryResultAsObservable$1(Paginator.java:131)

at reactor.core.publisher.FluxGenerate$GenerateSubscription.slowPath(FluxGenerate.java:271)

at reactor.core.publisher.FluxGenerate$GenerateSubscription.request(FluxGenerate.java:213)

at reactor.core.publisher.FluxMergeSequential$MergeSequentialMain.drain(FluxMergeSequential.java:430)

at reactor.core.publisher.FluxMergeSequential$MergeSequentialMain.innerComplete(FluxMergeSequential.java:335)

at reactor.core.publisher.FluxMergeSequential$MergeSequentialInner.onComplete(FluxMergeSequential.java:591)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxDoFinally$DoFinallySubscriber.onComplete(FluxDoFinally.java:128)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onComplete(MonoPeekTerminal.java:299)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:260)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:144)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.SerializedSubscriber.onComplete(SerializedSubscriber.java:146)

at reactor.core.publisher.FluxRetryWhen$RetryWhenMainSubscriber.onComplete(FluxRetryWhen.java:204)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.MonoFlatMap$FlatMapMain.secondComplete(MonoFlatMap.java:246)

at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:305)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:122)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.Operators$MonoInnerProducerBase.complete(Operators.java:2864)

at reactor.core.publisher.MonoSingle$SingleSubscriber.onComplete(MonoSingle.java:180)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.MonoFlatMap$FlatMapMain.secondComplete(MonoFlatMap.java:246)

at reactor.core.publisher.MonoFlatMap$FlatMapInner.onNext(MonoFlatMap.java:305)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:129)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.onNext(FluxHide.java:137)

at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:158)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.onNext(FluxHide.java:137)

at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onNext(MonoPeekTerminal.java:180)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:79)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.SerializedSubscriber.onNext(SerializedSubscriber.java:99)

at reactor.core.publisher.FluxRetryWhen$RetryWhenMainSubscriber.onNext(FluxRetryWhen.java:178)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:158)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.Operators$MonoInnerProducerBase.complete(Operators.java:2864)

at reactor.core.publisher.MonoSingle$SingleSubscriber.onComplete(MonoSingle.java:180)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onComplete(FluxPeekFuseable.java:277)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.onComplete(FluxHide.java:147)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxHide$SuppressFuseableSubscriber.onComplete(FluxHide.java:147)

at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:159)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.Operators$MonoInnerProducerBase.complete(Operators.java:2864)

at reactor.core.publisher.MonoSingle$SingleSubscriber.onComplete(MonoSingle.java:180)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxFlatMap$FlatMapMain.checkTerminated(FluxFlatMap.java:850)

at reactor.core.publisher.FluxFlatMap$FlatMapMain.drainLoop(FluxFlatMap.java:612)

at reactor.core.publisher.FluxFlatMap$FlatMapMain.innerComplete(FluxFlatMap.java:898)

at reactor.core.publisher.FluxFlatMap$FlatMapInner.onComplete(FluxFlatMap.java:1001)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxSwitchIfEmpty$SwitchIfEmptySubscriber.onComplete(FluxSwitchIfEmpty.java:85)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onComplete(FluxConcatArray.java:209)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.MonoIgnoreElements$IgnoreElementsSubscriber.onComplete(MonoIgnoreElements.java:89)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxTakeUntil$TakeUntilPredicateSubscriber.onComplete(FluxTakeUntil.java:122)

at reactor.core.publisher.FluxTakeUntil$TakeUntilPredicateSubscriber.onNext(FluxTakeUntil.java:100)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.FluxRepeatPredicate$RepeatPredicateSubscriber.onNext(FluxRepeatPredicate.java:86)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.FluxDoFinally$DoFinallySubscriber.onNext(FluxDoFinally.java:113)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:122)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:79)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onNext(TracingSubscriber.java:68)

at reactor.core.publisher.Operators$BaseFluxToMonoOperator.completePossiblyEmpty(Operators.java:2096)

at reactor.core.publisher.MonoCollectList$MonoCollectListSubscriber.onComplete(MonoCollectList.java:118)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxFlatMap$FlatMapMain.checkTerminated(FluxFlatMap.java:850)

at reactor.core.publisher.FluxFlatMap$FlatMapMain.drainLoop(FluxFlatMap.java:612)

at reactor.core.publisher.FluxFlatMap$FlatMapMain.innerComplete(FluxFlatMap.java:898)

at reactor.core.publisher.FluxFlatMap$FlatMapInner.onComplete(FluxFlatMap.java:1001)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onComplete(Operators.java:2230)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxFlatMap$FlatMapMain.checkTerminated(FluxFlatMap.java:850)

at reactor.core.publisher.FluxFlatMap$FlatMapMain.drainLoop(FluxFlatMap.java:612)

at reactor.core.publisher.FluxFlatMap$FlatMapMain.drain(FluxFlatMap.java:592)

at reactor.core.publisher.FluxFlatMap$FlatMapMain.onComplete(FluxFlatMap.java:469)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onComplete(FluxContextWrite.java:126)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxDoFinally$DoFinallySubscriber.onComplete(FluxDoFinally.java:128)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onComplete(Operators.java:2230)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:144)

at io.opentelemetry.javaagent.shaded.instrumentation.reactor.v3_1.TracingSubscriber.onComplete(TracingSubscriber.java:92)

at reactor.core.publisher.MonoCompletionStage$MonoCompletionStageSubscription.apply(MonoCompletionStage.java:122)

at reactor.core.publisher.MonoCompletionStage$MonoCompletionStageSubscription.apply(MonoCompletionStage.java:67)

at java.base/java.util.concurrent.CompletableFuture.uniHandle(CompletableFuture.java:934)

at java.base/java.util.concurrent.CompletableFuture$UniHandle.tryFire(CompletableFuture.java:911)

at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510)

at java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2179)

at com.azure.cosmos.implementation.directconnectivity.rntbd.RntbdRequestManager.messageReceived(RntbdRequestManager.java:1012)

at com.azure.cosmos.implementation.directconnectivity.rntbd.RntbdRequestManager.channelRead(RntbdRequestManager.java:226)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)

at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)

at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:346)

at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:318)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)

at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)

at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:436)

at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:253)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)

at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)

at io.netty.handler.timeout.IdleStateHandler.channelRead(IdleStateHandler.java:289)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)

at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)

at io.netty.handler.ssl.SslHandler.unwrap(SslHandler.java:1519)

at io.netty.handler.ssl.SslHandler.decodeJdkCompatible(SslHandler.java:1377)

at io.netty.handler.ssl.SslHandler.decode(SslHandler.java:1428)

at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:530)

at io.netty.handler.codec.ByteToMessageDecoder.callDecode(ByteToMessageDecoder.java:469)

at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:290)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)

at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412)

at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1357)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440)

at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420)

at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:868)

at io.netty.channel.epoll.AbstractEpollStreamChannel$EpollStreamUnsafe.epollInReady(AbstractEpollStreamChannel.java:799)

at io.netty.channel.epoll.AbstractEpollChannel$AbstractEpollUnsafe$1.run(AbstractEpollChannel.java:425)

at io.netty.util.concurrent.AbstractEventExecutor.runTask(AbstractEventExecutor.java:173)

at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:166)

at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:472)

at io.netty.channel.epoll.EpollEventLoop.run(EpollEventLoop.java:405)

at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:998)

at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)

at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)

at java.base/java.lang.Thread.run(Thread.java:1583)
```

**To Reproduce**
We have had difficulty reproducing this error locally and in our deployed environments. We suspect that this may be an issue with multithreaded querying in cosmos as ArrayList.add() does not throw an index out of bounds error when used appropriately.

***Code Snippet***
```
public class CustomizedRepositoryImpl implements CustomizedRepository {

private final CosmosTemplate cosmosTemplate;

...

private Page performGet(

String param1, String param2, List param3, Pageable pageRequest) {

String lookupQuery = "SELECT * FROM c "

+ "WHERE ARRAY_CONTAINS(c.params, {\"param1\": @param1, \"param2\": @param2}, true) "

+ "AND ARRAY_CONTAINS(@param3 , param3)";

SqlParameter param1 = new SqlParameter("@param1", param1);

SqlParameter param2 = new SqlParameter("@param2", param2);

SqlParameter param3 = new SqlParameter("@param3 ", param3);

SqlQuerySpec sqlQuerySpec =

new SqlQuerySpec(lookupQuery, param1 , param2 , param3);

return cosmosTemplate.runPaginationQuery(sqlQuerySpec, Pageable.ofSize(20), Object.class, Object.class);

}

}
```

**Expected behavior**
Retrieving Cosmos DB Entity

**Screenshots**
N/A

**Setup (please complete the following information):**
- OS: Linux
- Library: azure-cosmos:4.65.0
- Java version: 21
- App server/Environment: Azure
- Frameworks: Spring Boot

If you suspect a dependency version mismatch (e.g. you see `NoClassDefFoundError`, `NoSuchMethodError` or similar), please check out [Troubleshoot dependency version conflict article](https://aka.ms/azsdk/java/dependency/troubleshoot) first. If it doesn't provide solution for the problem, please provide:
- verbose dependency tree (`mvn dependency:tree -Dverbose`)
- exception message, full stack trace, and any available logs

**Additional context**
Add any other context about the problem here.

**Information Checklist**
Kindly make sure that you have added all the following information above and checkoff the required fields otherwise we will treat the issuer as an incomplete report
- [ x] Bug Description Added
- [ x] Repro Steps Added
- [ x] Setup information Added

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[BUG] Cosmos Library throwing IndexOutOfBounds Exception on ArrayList.add()

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