SpringBoot websocket integration test failed after upgrading to 4.0.0-RC1

here is my WebSocketConfig

here is the test WebSocketConfigTest

it's working in 4.0.0-M3, but not RC1, not sure how to fix, here is the error

2025-10-27T21:19:47.394+08:00 ERROR 14900 --- [cTaskExecutor-1] [                                                 ] o.s.w.s.s.client.XhrClientSockJsSession  : WebSocketHandler.afterConnectionEstablished threw exception in XhrClientSockJsSession[id='e4ce3e10faa84a028e5d65ab7c532b5b, url=http://localhost:9999/websocket/connect]

org.springframework.messaging.MessageDeliveryException: null
    at org.springframework.messaging.simp.stomp.DefaultStompSession.execute(DefaultStompSession.java:287) ~[spring-messaging-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.messaging.simp.stomp.DefaultStompSession.afterConnected(DefaultStompSession.java:403) ~[spring-messaging-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.socket.messaging.WebSocketStompClient$WebSocketTcpConnectionHandlerAdapter.afterConnectionEstablished(WebSocketStompClient.java:353) ~[spring-websocket-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.socket.handler.WebSocketHandlerDecorator.afterConnectionEstablished(WebSocketHandlerDecorator.java:70) ~[spring-websocket-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.socket.handler.LoggingWebSocketHandlerDecorator.afterConnectionEstablished(LoggingWebSocketHandlerDecorator.java:48) ~[spring-websocket-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.socket.sockjs.client.AbstractClientSockJsSession.handleOpenFrame(AbstractClientSockJsSession.java:240) ~[spring-websocket-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.socket.sockjs.client.AbstractClientSockJsSession.handleFrame(AbstractClientSockJsSession.java:222) ~[spring-websocket-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.socket.sockjs.client.RestTemplateXhrTransport$XhrReceiveExtractor.handleFrame(RestTemplateXhrTransport.java:258) ~[spring-websocket-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.socket.sockjs.client.RestTemplateXhrTransport$XhrReceiveExtractor.extractData(RestTemplateXhrTransport.java:242) ~[spring-websocket-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:757) ~[spring-web-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:715) ~[spring-web-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.socket.sockjs.client.RestTemplateXhrTransport.lambda$connectInternal$0(RestTemplateXhrTransport.java:119) ~[spring-websocket-7.0.0-RC2.jar:7.0.0-RC2]
    at java.base/java.lang.Thread.run(Thread.java:1583) ~[na:na]
Caused by: org.springframework.web.client.HttpClientErrorException$NotFound: 404  on POST request for "http://localhost:9999/websocket/connect/230/e4ce3e10faa84a028e5d65ab7c532b5b/xhr_send": [no body]
    at org.springframework.web.client.HttpClientErrorException.create(HttpClientErrorException.java:115) ~[spring-web-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:145) ~[spring-web-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:120) ~[spring-web-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:807) ~[spring-web-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:756) ~[spring-web-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:715) ~[spring-web-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.socket.sockjs.client.RestTemplateXhrTransport.executeSendRequestInternal(RestTemplateXhrTransport.java:145) ~[spring-websocket-7.0.0-RC2.jar:7.0.0-RC2]
    at org.springframework.web.socket.sockjs.client.AbstractXhrTransport.executeSendRequest(AbstractXhrTransport.java:151) ~[spring-websocket-7.0.0-RC2.jar:7.0.0-RC2]

kindly suggest

Thank you

Comment From: wilkinsona

Thanks for trying out the RC. Unfortunately, the supplied sample is too complex for us to investigate. Specifically, it contains many dependency, classes and tests that are unrelated to WebSocket. Please reduce it down to something that contains the bare minimum that's required for the failure to occur and we can take another look.

Comment From: mjd507

Thank you, here is the minimum project that can reproduce the issue.

https://github.com/mjd507/websocket-test

Comment From: snicoll

Thanks. I can indeed reproduce with RC1 and it works with M3. However, if I downgrade Spring Security from 7.0.0-RC1 to 7.0.0-M3 this works with Spring Boot RC1 as well. You can validate that by adding the following to the build of your sample:

extra["spring-security.version"] = "7.0.0-M3"

I cannot transfer this issue to Spring Security unfortunately. Please submit it with a link to this issue at https://github.com/spring-projects/spring-security/issues/new