# Spring WebFlux 7 (Spring Boot 4): NoSuchMethodError in DispatcherHandlerInstrumentation **URL:** \ **Category:** Elastic Agent\ **Created:** [June 11, 2026, 6:02pm UTC](https://discuss.elastic.co/t/spring-webflux-7-spring-boot-4-nosuchmethoderror-in-dispatcherhandlerinstrumentation/386817 "2026-06-11T18:02:13Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![VVK](https://avatars.discourse-cdn.com/v4/letter/v/e47774/32.png) [@VVK](https://discuss.elastic.co/u/VVK)\ **Post date:** [June 11, 2026, 6:02pm UTC](https://discuss.elastic.co/t/spring-webflux-7-spring-boot-4-nosuchmethoderror-in-dispatcherhandlerinstrumentation/386817/1 "2026-06-11T18:02:13Z")
> > > \## Description > > The agent's WebFlux instrumentation throws \`NoSuchMethodError\` o…n Spring Framework 7 (Spring Boot 4) with Netty. > > PR #4397 added experimental Spring Boot 4 support for Spring MVC (servlet stack), but the \*\*WebFlux (reactive stack) instrumentation was not updated\*\* and remains incompatible with Spring Framework 7. > > \## Environment > > \- \*\*Agent version:\*\* 1.55.6 > \- \*\*Spring Boot:\*\* 4.0.x > \- \*\*Spring Framework:\*\* 7.0.2 > \- \*\*Spring WebFlux:\*\* 7.0.2 > \- \*\*Reactor Netty:\*\* 1.3.1 > \- \*\*Netty:\*\* 4.2.9.Final > \- \*\*JDK:\*\* 21 > > \## Stack trace > > \`\`\` > \[reactor-http-nio-2\] ERROR co.elastic.apm.agent.bci.IndyBootstrap - Advice threw an exception, this should never happen! > java.lang.NoSuchMethodError: 'java.util.List org.springframework.http.HttpHeaders.get(java.lang.Object)' > at co.elastic.apm.agent.springwebflux.DispatcherHandlerInstrumentation$HandleAdvice.onEnter(DispatcherHandlerInstrumentation.java:64) ~\[elastic-apm-agent-aefc330832b1a172028a4ec17f6d4d20-29542a5269d2cc8773f457e12848a276.jar:1.55.6\] > at org.springframework.web.reactive.DispatcherHandler.handle(DispatcherHandler.java:139) ~\[spring-webflux-7.0.2.jar:7.0.2\] > at org.springframework.web.server.handler.DefaultWebFilterChain.lambda$filter$0(DefaultWebFilterChain.java:107) ~\[spring-web-7.0.2.jar:7.0.2\] > at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:45) ~\[reactor-core-3.6.11.jar:3.6.11\] > at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:76) ~\[reactor-core-3.6.11.jar:3.6.11\] > at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:53) ~\[reactor-core-3.6.11.jar:3.6.11\] > at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:76) ~\[reactor-core-3.6.11.jar:3.6.11\] > at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:53) ~\[reactor-core-3.6.11.jar:3.6.11\] > at reactor.core.publisher.Mono.subscribe(Mono.java:4576) ~\[reactor-core-3.6.11.jar:3.6.11\] > at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.subscribeNext(MonoIgnoreThen.java:265) ~\[reactor-core-3.6.11.jar:3.6.11\] > at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:51) ~\[reactor-core-3.6.11.jar:3.6.11\] > at reactor.core.publisher.Mono.subscribe(Mono.java:4576) ~\[reactor-core-3.6.11.jar:3.6.11\] > at reactor.core.publisher.MonoIgnoreThen$ThenIgnoreMain.subscribeNext(MonoIgnoreThen.java:265) ~\[reactor-core-3.6.11.jar:3.6.11\] > at reactor.core.publisher.MonoIgnoreThen.subscribe(MonoIgnoreThen.java:51) ~\[reactor-core-3.6.11.jar:3.6.11\] > at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:76) ~\[reactor-core-3.6.11.jar:3.6.11\] > at reactor.core.publisher.MonoDeferContextual.subscribe(MonoDeferContextual.java:55) ~\[reactor-core-3.6.11.jar:3.6.11\] > at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:76) ~\[reactor-core-3.6.11.jar:3.6.11\] > at reactor.netty.http.server.HttpServer$HttpServerHandle.onStateChange(HttpServer.java:1344) ~\[reactor-netty-http-1.3.1.jar:1.3.1\] > at reactor.netty.ReactorNetty$CompositeConnectionObserver.onStateChange(ReactorNetty.java:730) ~\[reactor-netty-core-1.3.1.jar:1.3.1\] > at reactor.netty.transport.ServerTransport$ChildObserver.onStateChange(ServerTransport.java:489) ~\[reactor-netty-core-1.3.1.jar:1.3.1\] > at reactor.netty.http.server.HttpServerOperations.handleDefaultHttpRequest(HttpServerOperations.java:863) ~\[reactor-netty-http-1.3.1.jar:1.3.1\] > at reactor.netty.http.server.HttpServerOperations.onInboundNext(HttpServerOperations.java:789) ~\[reactor-netty-http-1.3.1.jar:1.3.1\] > at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:115) ~\[reactor-netty-core-1.3.1.jar:1.3.1\] > at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:356) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at reactor.netty.http.server.HttpTrafficHandler.channelRead(HttpTrafficHandler.java:283) ~\[reactor-netty-http-1.3.1.jar:1.3.1\] > at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:354) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:434) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:361) ~\[netty-codec-base-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:325) ~\[netty-codec-base-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:249) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:354) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1429) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:918) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:172) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe.handle(AbstractNioChannel.java:445) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.channel.nio.NioIoHandler$DefaultNioRegistration.handle(NioIoHandler.java:388) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.channel.nio.NioIoHandler.processSelectedKey(NioIoHandler.java:596) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.channel.nio.NioIoHandler.processSelectedKeysOptimized(NioIoHandler.java:571) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.channel.nio.NioIoHandler.processSelectedKeys(NioIoHandler.java:512) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.channel.nio.NioIoHandler.run(NioIoHandler.java:484) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.channel.SingleThreadIoEventLoop.runIo(SingleThreadIoEventLoop.java:225) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.channel.SingleThreadIoEventLoop.run(SingleThreadIoEventLoop.java:196) ~\[netty-transport-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.util.concurrent.SingleThreadEventExecutor$5.run(SingleThreadEventExecutor.java:1195) ~\[netty-common-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~\[netty-common-4.2.9.Final.jar:4.2.9.Final\] > at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~\[netty-common-4.2.9.Final.jar:4.2.9.Final\] > at java.lang.Thread.run(Thread.java:1583) \[?:?\] > \`\`\` > > \## Expected behavior > > The WebFlux instrumentation should work with Spring Framework 7 / Spring Boot 4, similar to the MVC support added in #4397. Hi there, When the fix will be released? Looking eagerly for above fix. Current latest build 1.55.6 has been released in April 2nd week. Regards ---
**Author:** ![VVK](https://avatars.discourse-cdn.com/v4/letter/v/e47774/32.png) [@VVK](https://discuss.elastic.co/u/VVK)\ **Post date:** [June 16, 2026, 5:09am UTC](https://discuss.elastic.co/t/spring-webflux-7-spring-boot-4-nosuchmethoderror-in-dispatcherhandlerinstrumentation/386817/2 "2026-06-16T05:09:49Z")
> **[1.56.0 - Elastic APM Java Agent release notes | APM Java agent](https://www.elastic.co/docs/release-notes/apm/agents/java#elastic-apm-java-agent-1-56-0-release-notes)** > > Release date: June 15, 2026 | Review the changes, fixes, and more in each version of Elastic APM Java Agent. To check for security updates, go to Security announcements for the Elastic... thanks.. will check soon.