spring-projects / spring-projects/spring-ai

After the mcp server restarts, the client will return 404.

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Description

Bug description
After the mcp server restarts, the client will return 404.

Environment
Client:


        <dependency>
            <groupId>org.springframework.ai</groupId>
            <artifactId>spring-ai-starter-mcp-client-webflux</artifactId>
        </dependency>

spring:
    ai:
    mcp:
      client:
        name: mcp-client
        enabled: true
        type: async
        request-timeout: 30s
        sse:
          connections:
            music-mcp-server:
              url: http://localhost:8083
              sse-endpoint: /sse

   @Autowired
    private final ObjectProvider<List<ToolCallbackProvider>> listObjectProvider;

 this.chatClient = builder
                .defaultSystem("你是一个智能助手，帮助用户解决相关问题，上下文和历史信息帮助你更好了解用户需求，但记住你不仅可以根据上下文来回答内容，而且你也可以调用工具帮助用户查询，始终遵守用户的指令。")
                .defaultAdvisors(
                        MessageChatMemoryAdvisor.builder(chatMemory).build(),
                .defaultToolCallbacks(listObjectProvider.getIfAvailable().toArray(new ToolCallbackProvider[0]))
                .build();

Server:

    <dependency>
            <groupId>org.springframework.ai</groupId>
            <artifactId>spring-ai-starter-mcp-server-webmvc</artifactId>
        </dependency>

    mcp:
      client:
        name: mcp-client
        enabled: true
        type: async
        request-timeout: 30s
        sse:
          connections:
            music-mcp-server:
              url: http://localhost:8083
              sse-endpoint: /sse

Steps to reproduce

MCP server restarts. The client will display:

2025-05-27T10:52:04.339+08:00 ERROR 19032 --- [ai-project] [ient-1-Worker-0] i.m.c.t.WebFluxSseClientTransport        : Fatal SSE error, not retrying: 200 OK from GET http://localhost:8083/sse, but response failed with cause: java.io.IOException: chunked transfer encoding, state: READING_LENGTH
2025-05-27T10:52:04.340+08:00 ERROR 19032 --- [ai-project] [ient-1-Worker-0] reactor.core.publisher.Operators         : Operator called default onErrorDropped

reactor.core.Exceptions$ErrorCallbackNotImplemented: org.springframework.web.reactive.function.client.WebClientResponseException: 200 OK from GET http://localhost:8083/sse, but response failed with cause: java.io.IOException: chunked transfer encoding, state: READING_LENGTH
Caused by: org.springframework.web.reactive.function.client.WebClientResponseException: 200 OK from GET http://localhost:8083/sse, but response failed with cause: java.io.IOException: chunked transfer encoding, state: READING_LENGTH
	at org.springframework.web.reactive.function.client.WebClientResponseException.create(WebClientResponseException.java:337) ~[spring-webflux-6.1.12.jar:6.1.12]
	at org.springframework.web.reactive.function.client.DefaultClientResponse.lambda$createException$1(DefaultClientResponse.java:214) ~[spring-webflux-6.1.12.jar:6.1.12]
	at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:106) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxOnErrorReturn$ReturnSubscriber.onError(FluxOnErrorReturn.java:199) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxDefaultIfEmpty$DefaultIfEmptySubscriber.onError(FluxDefaultIfEmpty.java:156) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onError(FluxOnAssembly.java:544) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onError(FluxMapFuseable.java:142) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onError(FluxContextWrite.java:121) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onError(FluxMapFuseable.java:340) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onError(FluxFilterFuseable.java:382) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.MonoCollect$CollectSubscriber.onError(MonoCollect.java:135) ~[reactor-core-3.6.9.jar:3.6.9]
	at org.springframework.http.client.reactive.AbstractClientHttpResponse$SingleSubscriberPublisher.subscribe(AbstractClientHttpResponse.java:116) ~[spring-web-6.1.12.jar:6.1.12]
	at reactor.core.publisher.FluxSource.subscribe(FluxSource.java:71) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.Mono.subscribe(Mono.java:4576) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onError(FluxOnErrorResume.java:103) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxOnAssembly$OnAssemblySubscriber.onError(FluxOnAssembly.java:544) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxConcatMapNoPrefetch$FluxConcatMapNoPrefetchSubscriber.maybeOnError(FluxConcatMapNoPrefetch.java:327) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxConcatMapNoPrefetch$FluxConcatMapNoPrefetchSubscriber.onError(FluxConcatMapNoPrefetch.java:221) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxBufferPredicate$BufferPredicateSubscriber.onError(FluxBufferPredicate.java:346) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxPeekFuseable$PeekFuseableConditionalSubscriber.onError(FluxPeekFuseable.java:553) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onError(FluxMapFuseable.java:340) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onError(FluxContextWrite.java:121) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxDoFinally$DoFinallySubscriber.onError(FluxDoFinally.java:119) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxConcatArray$ConcatArraySubscriber.onError(FluxConcatArray.java:186) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxFlattenIterable$FlattenIterableSubscriber.drainAsync(FluxFlattenIterable.java:351) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxFlattenIterable$FlattenIterableSubscriber.drain(FluxFlattenIterable.java:724) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxFlattenIterable$FlattenIterableSubscriber.onError(FluxFlattenIterable.java:263) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxPublish$PublishSubscriber.checkTerminated(FluxPublish.java:625) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxPublish$PublishSubscriber.drain(FluxPublish.java:494) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxPublish$PublishSubscriber.onError(FluxPublish.java:336) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onError(FluxContextWrite.java:121) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onError(FluxMapFuseable.java:340) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxFlattenIterable$FlattenIterableSubscriber.drainAsync(FluxFlattenIterable.java:351) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxFlattenIterable$FlattenIterableSubscriber.drain(FluxFlattenIterable.java:724) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.core.publisher.FluxFlattenIterable$FlattenIterableSubscriber.onError(FluxFlattenIterable.java:263) ~[reactor-core-3.6.9.jar:3.6.9]
	at reactor.adapter.JdkFlowAdapter$SubscriberToRS.onError(JdkFlowAdapter.java:155) ~[reactor-core-3.6.9.jar:3.6.9]
	at java.net.http/jdk.internal.net.http.ResponseSubscribers$PublishingBodySubscriber.complete(ResponseSubscribers.java:960) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.ResponseSubscribers$PublishingBodySubscriber.lambda$new$1(ResponseSubscribers.java:886) ~[java.net.http:na]
	at java.base/java.util.concurrent.CompletableFuture.uniAcceptNow(CompletableFuture.java:757) ~[na:na]
	at java.base/java.util.concurrent.CompletableFuture.uniAcceptStage(CompletableFuture.java:735) ~[na:na]
	at java.base/java.util.concurrent.CompletableFuture.thenAccept(CompletableFuture.java:2214) ~[na:na]
	at java.net.http/jdk.internal.net.http.ResponseSubscribers$PublishingBodySubscriber.lambda$new$2(ResponseSubscribers.java:886) ~[java.net.http:na]
	at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:863) ~[na:na]
	at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:841) ~[na:na]
	at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510) ~[na:na]
	at java.base/java.util.concurrent.CompletableFuture.completeExceptionally(CompletableFuture.java:2194) ~[na:na]
	at java.net.http/jdk.internal.net.http.ResponseSubscribers$PublishingBodySubscriber.signalError(ResponseSubscribers.java:968) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.ResponseSubscribers$PublishingBodySubscriber.onError(ResponseSubscribers.java:1044) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.common.HttpBodySubscriberWrapper.propagateError(HttpBodySubscriberWrapper.java:171) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.common.HttpBodySubscriberWrapper.complete(HttpBodySubscriberWrapper.java:310) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.common.HttpBodySubscriberWrapper.onError(HttpBodySubscriberWrapper.java:396) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.Http1Response.lambda$readBody$1(Http1Response.java:347) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.ResponseContent$ChunkedBodyParser.onError(ResponseContent.java:185) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.Http1Response$BodyReader.onReadError(Http1Response.java:677) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.Http1AsyncReceiver.checkForErrors(Http1AsyncReceiver.java:302) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.Http1AsyncReceiver.flush(Http1AsyncReceiver.java:268) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.common.SequentialScheduler$LockingRestartableTask.run(SequentialScheduler.java:182) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:149) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:207) ~[java.net.http:na]
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) ~[na:na]
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) ~[na:na]
	at java.base/java.lang.Thread.run(Thread.java:1583) ~[na:na]
Caused by: java.io.IOException: chunked transfer encoding, state: READING_LENGTH
	at java.net.http/jdk.internal.net.http.common.Utils.wrapWithExtraDetail(Utils.java:391) ~[java.net.http:na]
	Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
	*__checkpoint ⇢ Body from GET http://localhost:8083/sse [DefaultClientResponse]
Original Stack Trace:
		at java.net.http/jdk.internal.net.http.common.Utils.wrapWithExtraDetail(Utils.java:391) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.Http1Response$BodyReader.onReadError(Http1Response.java:676) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.Http1AsyncReceiver.checkForErrors(Http1AsyncReceiver.java:302) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.Http1AsyncReceiver.flush(Http1AsyncReceiver.java:268) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.common.SequentialScheduler$LockingRestartableTask.run(SequentialScheduler.java:182) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:149) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:207) ~[java.net.http:na]
		at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) ~[na:na]
		at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) ~[na:na]
		at java.base/java.lang.Thread.run(Thread.java:1583) ~[na:na]
Caused by: java.io.EOFException: EOF reached while reading
	at java.net.http/jdk.internal.net.http.Http1AsyncReceiver$Http1TubeSubscriber.onComplete(Http1AsyncReceiver.java:601) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.SocketTube$InternalReadPublisher$ReadSubscription.signalCompletion(SocketTube.java:648) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.SocketTube$InternalReadPublisher$InternalReadSubscription.read(SocketTube.java:853) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.SocketTube$SocketFlowTask.run(SocketTube.java:181) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:207) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:280) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.common.SequentialScheduler.runOrSchedule(SequentialScheduler.java:233) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.SocketTube$InternalReadPublisher$InternalReadSubscription.signalReadable(SocketTube.java:782) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.SocketTube$InternalReadPublisher$ReadEvent.signalEvent(SocketTube.java:965) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.SocketTube$SocketFlowEvent.handle(SocketTube.java:253) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.HttpClientImpl$SelectorManager.handleEvent(HttpClientImpl.java:1467) ~[java.net.http:na]
	at java.net.http/jdk.internal.net.http.HttpClientImpl$SelectorManager.lambda$run$3(HttpClientImpl.java:1412) ~[java.net.http:na]
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1596) ~[na:na]
	at java.net.http/jdk.internal.net.http.HttpClientImpl$SelectorManager.run(HttpClientImpl.java:1412) ~[java.net.http:na]

if you ask some question showed

2025-05-27T10:52:54.416+08:00 ERROR 19032 --- [ai-project] [nio-8082-exec-6] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed: org.springframework.web.reactive.function.client.WebClientResponseException$NotFound: 404 Not Found from POST http://localhost:8083/mcp/message] with root cause

org.springframework.web.reactive.function.client.WebClientResponseException$NotFound: 404 Not Found from POST http://localhost:8083/mcp/message
	at org.springframework.web.reactive.function.client.WebClientResponseException.create(WebClientResponseException.java:324) ~[spring-webflux-6.1.12.jar:6.1.12]
	Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
	*__checkpoint ⇢ 404 NOT_FOUND from POST http://localhost:8083/mcp/message [DefaultWebClient]
Original Stack Trace:
		at org.springframework.web.reactive.function.client.WebClientResponseException.create(WebClientResponseException.java:324) ~[spring-webflux-6.1.12.jar:6.1.12]
		at org.springframework.web.reactive.function.client.DefaultClientResponse.lambda$createException$1(DefaultClientResponse.java:214) ~[spring-webflux-6.1.12.jar:6.1.12]
		at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:106) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxOnErrorReturn$ReturnSubscriber.onNext(FluxOnErrorReturn.java:162) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxDefaultIfEmpty$DefaultIfEmptySubscriber.onNext(FluxDefaultIfEmpty.java:122) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:129) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onNext(FluxContextWrite.java:107) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:299) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:337) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.Operators$BaseFluxToMonoOperator.completePossiblyEmpty(Operators.java:2097) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.MonoCollect$CollectSubscriber.onComplete(MonoCollect.java:145) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxPublish$PublishSubscriber.checkTerminated(FluxPublish.java:634) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxPublish$PublishSubscriber.drain(FluxPublish.java:494) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxPublish$PublishSubscriber.onComplete(FluxPublish.java:355) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onComplete(FluxContextWrite.java:126) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onComplete(FluxMapFuseable.java:350) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxFlattenIterable$FlattenIterableSubscriber.drainAsync(FluxFlattenIterable.java:371) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxFlattenIterable$FlattenIterableSubscriber.drain(FluxFlattenIterable.java:724) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxFlattenIterable$FlattenIterableSubscriber.onComplete(FluxFlattenIterable.java:273) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.adapter.JdkFlowAdapter$SubscriberToRS.onComplete(JdkFlowAdapter.java:160) ~[reactor-core-3.6.9.jar:3.6.9]
		at java.net.http/jdk.internal.net.http.ResponseSubscribers$PublishingBodySubscriber.complete(ResponseSubscribers.java:955) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.ResponseSubscribers$PublishingBodySubscriber.lambda$new$1(ResponseSubscribers.java:886) ~[java.net.http:na]
		at java.base/java.util.concurrent.CompletableFuture.uniAcceptNow(CompletableFuture.java:757) ~[na:na]
		at java.base/java.util.concurrent.CompletableFuture.uniAcceptStage(CompletableFuture.java:735) ~[na:na]
		at java.base/java.util.concurrent.CompletableFuture.thenAccept(CompletableFuture.java:2214) ~[na:na]
		at java.net.http/jdk.internal.net.http.ResponseSubscribers$PublishingBodySubscriber.lambda$new$2(ResponseSubscribers.java:886) ~[java.net.http:na]
		at java.base/java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:863) ~[na:na]
		at java.base/java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:841) ~[na:na]
		at java.base/java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:510) ~[na:na]
		at java.base/java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:2179) ~[na:na]
		at java.net.http/jdk.internal.net.http.ResponseSubscribers$PublishingBodySubscriber.signalComplete(ResponseSubscribers.java:972) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.ResponseSubscribers$PublishingBodySubscriber.onComplete(ResponseSubscribers.java:1058) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.common.HttpBodySubscriberWrapper.complete(HttpBodySubscriberWrapper.java:293) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.common.HttpBodySubscriberWrapper.onComplete(HttpBodySubscriberWrapper.java:401) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.ResponseContent$ChunkedBodyParser.accept(ResponseContent.java:220) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.ResponseContent$ChunkedBodyParser.accept(ResponseContent.java:131) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.Http1Response$BodyReader.handle(Http1Response.java:707) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.Http1Response$BodyReader.handle(Http1Response.java:635) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.Http1Response$Receiver.accept(Http1Response.java:527) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.Http1Response$BodyReader.tryAsyncReceive(Http1Response.java:665) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.Http1AsyncReceiver.flush(Http1AsyncReceiver.java:233) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.common.SequentialScheduler$LockingRestartableTask.run(SequentialScheduler.java:182) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.common.SequentialScheduler$CompleteRestartableTask.run(SequentialScheduler.java:149) ~[java.net.http:na]
		at java.net.http/jdk.internal.net.http.common.SequentialScheduler$SchedulableTask.run(SequentialScheduler.java:207) ~[java.net.http:na]
		at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) ~[na:na]
		at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) ~[na:na]
		at java.base/java.lang.Thread.run(Thread.java:1583) ~[na:na]
	Suppressed: java.lang.Exception: #block terminated with an error
		at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:104) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.Mono.block(Mono.java:1779) ~[reactor-core-3.6.9.jar:3.6.9]
		at org.springframework.ai.mcp.AsyncMcpToolCallback.call(AsyncMcpToolCallback.java:117) ~[spring-ai-mcp-1.0.0.jar:1.0.0]
		at org.springframework.ai.mcp.AsyncMcpToolCallback.call(AsyncMcpToolCallback.java:123) ~[spring-ai-mcp-1.0.0.jar:1.0.0]
		at org.springframework.ai.model.tool.DefaultToolCallingManager.lambda$executeToolCall$5(DefaultToolCallingManager.java:224) ~[spring-ai-model-1.0.0.jar:1.0.0]
		at io.micrometer.observation.Observation.observe(Observation.java:565) ~[micrometer-observation-1.12.9.jar:1.12.9]
		at org.springframework.ai.model.tool.DefaultToolCallingManager.executeToolCall(DefaultToolCallingManager.java:221) ~[spring-ai-model-1.0.0.jar:1.0.0]
		at org.springframework.ai.model.tool.DefaultToolCallingManager.executeToolCalls(DefaultToolCallingManager.java:137) ~[spring-ai-model-1.0.0.jar:1.0.0]
		at org.springframework.ai.openai.OpenAiChatModel.lambda$internalStream$10(OpenAiChatModel.java:369) ~[spring-ai-openai-1.0.0.jar:1.0.0]
		at reactor.core.publisher.FluxDefer.subscribe(FluxDefer.java:46) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.publisher.FluxSubscribeOn$SubscribeOnSubscriber.run(FluxSubscribeOn.java:194) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.scheduler.WorkerTask.call(WorkerTask.java:84) ~[reactor-core-3.6.9.jar:3.6.9]
		at reactor.core.scheduler.WorkerTask.call(WorkerTask.java:37) ~[reactor-core-3.6.9.jar:3.6.9]
		at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:317) ~[na:na]
		at java.base/java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304) ~[na:na]
		at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1144) ~[na:na]
		at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:642) ~[na:na]
		at java.base/java.lang.Thread.run(Thread.java:1583) ~[na:na]

Expected behavior
Support reconnection. After the mcp server restarts.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with WebFluxSseClientTransport and the GET http://localhost:8083/sse failure shown in the report; inspect how the MCP SSE client handles a server restart and chunked-transfer error. Reproduce the restart sequence with the provided WebFlux client and server configuration, and consider the issue done when the client reconnects without the reported 404 or transport error.

Written by the indexing model from the issue text.

Assessment

Tech stack
java, spring
Domain
api, backend, networking
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
30/100

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