# Method not found java.util.Set org.springframework.http.HttpHeaders.entrySet()

**URL:** <https://discuss.elastic.co/t/method-not-found-java-util-set-org-springframework-http-httpheaders-entryset/387412>\
**Category:** APM\
**Tags:** java\
**Created:** [June 30, 2026, 3:19pm UTC](https://discuss.elastic.co/t/method-not-found-java-util-set-org-springframework-http-httpheaders-entryset/387412 "2026-06-30T15:19:51Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![VVK](https://avatars.discourse-cdn.com/v4/letter/v/e47774/32.png) [@VVK](https://discuss.elastic.co/u/VVK)\
**Post date:** [June 30, 2026, 3:19pm UTC](https://discuss.elastic.co/t/method-not-found-java-util-set-org-springframework-http-httpheaders-entryset/387412/1 "2026-06-30T15:19:51Z")

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This message comes here because while creating issue, it is recommended to discuss here before creating an issue in github.

I am using 1.56.0 java apm agent which is supporting springboot 4.0 and spring webflux on experimental basis according to release notes.

I get following exception

```auto
java.lang.NoSuchMethodError: 'java.util.Set org.springframework.http.HttpHeaders.entrySet()' 
     at co.elastic.apm.agent.springwebflux.WebfluxHelper.copyHeaders(WebfluxHelper.java:316) 	
     at co.elastic.apm.agent.springwebflux.WebfluxHelper.fillRequest(WebfluxHelper.java:286) 	
     at co.elastic.apm.agent.springwebflux.WebfluxHelper.endTransaction(WebfluxHelper.java:177) 	
     at co.elastic.apm.agent.springwebflux.TransactionAwareSubscriber.onComplete(TransactionAwareSubscriber.java:177) 	
     at co.elastic.apm.agent.reactor.TracedSubscriber.onComplete(TracedSubscriber.java:141) at

```

Next: I looked at

> <https://github.com/elastic/apm-agent-java/blob/main/apm-agent-plugins/apm-spring-webflux/apm-spring-webflux-spring5/src/main/java/co/elastic/apm/agent/springwebflux/WebfluxHelper.java#L286>

And understood that as an end consumer I **can disable capture of headers** as temporary workaround.

My dependencies are :

```auto
+- org.springframework.boot:spring-boot-starter-webflux:jar:4.0.7:compile
   \- org.springframework.boot:spring-boot-webflux:jar:4.0.7:compile
      +- org.springframework:spring-webflux:jar:7.0.8:compile

```

Let me know whether I need to create github issue.

---

<div class="post-metadata">

**Author:** ![Sylvain\_Juge](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/sylvain_juge/32/55521_2.png) [@Sylvain\_Juge](https://discuss.elastic.co/u/Sylvain_Juge)\
**Post date:** [July 1, 2026, 7:27am UTC](https://discuss.elastic.co/t/method-not-found-java-util-set-org-springframework-http-httpheaders-entryset/387412/2 "2026-07-01T07:27:14Z")

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Hi !  
There is already [a PR](https://github.com/elastic/apm-agent-java/pull/4515) that attempts to fix this, it has a few build failures currently and probably still needs a bit of work to be ready to be merged.