Open
Description
Bug description
Minimal Spring Boot application with Spring AI WebMVC MCP Server produces a lot of errors and warnings when any MCP clients connects to it. MCP Clients also randomly disconnects and reconnects to the MCP Server.
2025-05-07T21:33:51.842+02:00 ERROR 64151 --- [io-8080-exec-10] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session a2c209b5-4f6a-4675-8c4c-39733c6b5823: null
2025-05-07T21:33:51.849+02:00 WARN 64151 --- [nio-8080-exec-8] .w.s.m.s.DefaultHandlerExceptionResolver : Ignoring exception, response committed already: org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class java.util.LinkedHashMap] with preset Content-Type 'text/event-stream'
2025-05-07T21:33:51.850+02:00 WARN 64151 --- [nio-8080-exec-8] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class java.util.LinkedHashMap] with preset Content-Type 'text/event-stream']
2025-05-07T21:33:54.037+02:00 INFO 64151 --- [nio-8080-exec-7] i.m.server.McpAsyncServer : Client initialize request - Protocol: 2024-11-05, Capabilities: ClientCapabilities[experimental=null, roots=RootCapabilities[listChanged=false], sampling=null], Info: Implementation[name=cursor-vscode, version=1.0.0]
2025-05-07T21:33:54.037+02:00 INFO 64151 --- [nio-8080-exec-4] i.m.server.McpAsyncServer : Client initialize request - Protocol: 2024-11-05, Capabilities: ClientCapabilities[experimental=null, roots=RootCapabilities[listChanged=false], sampling=null], Info: Implementation[name=cursor-vscode, version=1.0.0]
2025-05-07T21:33:54.037+02:00 ERROR 64151 --- [nio-8080-exec-7] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session a2c209b5-4f6a-4675-8c4c-39733c6b5823: Cannot invoke "org.apache.catalina.connector.OutputBuffer.isBlocking()" because "this.ob" is null
2025-05-07T21:33:54.037+02:00 ERROR 64151 --- [nio-8080-exec-4] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session a2c209b5-4f6a-4675-8c4c-39733c6b5823: Cannot invoke "org.apache.catalina.connector.OutputBuffer.isBlocking()" because "this.ob" is null
2025-05-07T21:33:54.038+02:00 ERROR 64151 --- [nio-8080-exec-4] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 1c57403f-180f-4079-a8ca-b9554aaf383a: null
2025-05-07T21:33:54.038+02:00 ERROR 64151 --- [nio-8080-exec-4] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 5c0cb168-06fb-4981-83f2-604789055d4a: ServletOutputStream failed to flush: java.io.IOException: Broken pipe
2025-05-07T21:33:54.039+02:00 ERROR 64151 --- [nio-8080-exec-4] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 5e0c7216-87ce-4dc6-a418-de8e4297f5a8: ServletOutputStream failed to flush: java.io.IOException: Broken pipe
2025-05-07T21:33:54.039+02:00 ERROR 64151 --- [nio-8080-exec-5] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] threw exception
java.nio.BufferOverflowException: null
at java.base/java.nio.HeapByteBuffer.put(HeapByteBuffer.java:238) ~[na:na]
at org.apache.catalina.connector.OutputBuffer.transfer(OutputBuffer.java:802) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.connector.OutputBuffer.append(OutputBuffer.java:670) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.connector.OutputBuffer.writeBytes(OutputBuffer.java:377) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.connector.OutputBuffer.write(OutputBuffer.java:355) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.connector.CoyoteOutputStream.write(CoyoteOutputStream.java:102) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.springframework.web.context.request.async.StandardServletAsyncWebRequest$LifecycleServletOutputStream.write(StandardServletAsyncWebRequest.java:401) ~[spring-web-6.2.6.jar:6.2.6]
at java.base/java.io.OutputStream.write(OutputStream.java:124) ~[na:na]
at org.springframework.web.servlet.function.SseServerResponse$DefaultSseBuilder.send(SseServerResponse.java:143) ~[spring-webmvc-6.2.6.jar:6.2.6]
at org.springframework.web.servlet.function.SseServerResponse$DefaultSseBuilder.writeString(SseServerResponse.java:205) ~[spring-webmvc-6.2.6.jar:6.2.6]
at org.springframework.web.servlet.function.SseServerResponse$DefaultSseBuilder.data(SseServerResponse.java:193) ~[spring-webmvc-6.2.6.jar:6.2.6]
at io.modelcontextprotocol.server.transport.WebMvcSseServerTransport.lambda$sendMessage$0(WebMvcSseServerTransport.java:181) ~[mcp-spring-webmvc-0.7.0.jar:0.7.0]
at java.base/java.util.concurrent.ConcurrentHashMap$ValuesView.forEach(ConcurrentHashMap.java:4783) ~[na:na]
at io.modelcontextprotocol.server.transport.WebMvcSseServerTransport.lambda$sendMessage$1(WebMvcSseServerTransport.java:179) ~[mcp-spring-webmvc-0.7.0.jar:0.7.0]
at reactor.core.publisher.MonoRunnable.subscribe(MonoRunnable.java:49) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribe(Mono.java:4576) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribeWith(Mono.java:4641) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribe(Mono.java:4403) ~[reactor-core-3.7.5.jar:3.7.5]
at io.modelcontextprotocol.spec.DefaultMcpSession.lambda$new$0(DefaultMcpSession.java:138) ~[mcp-0.7.0.jar:0.7.0]
at reactor.core.publisher.LambdaMonoSubscriber.onNext(LambdaMonoSubscriber.java:171) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:79) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:129) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2570) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:171) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2366) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onSubscribe(FluxOnErrorResume.java:74) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:96) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:55) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:76) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:53) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribe(Mono.java:4576) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribeWith(Mono.java:4641) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribe(Mono.java:4542) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribe(Mono.java:4478) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribe(Mono.java:4450) ~[reactor-core-3.7.5.jar:3.7.5]
at io.modelcontextprotocol.spec.DefaultMcpSession.lambda$new$3(DefaultMcpSession.java:138) ~[mcp-0.7.0.jar:0.7.0]
at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:196) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2570) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.request(FluxPeekFuseable.java:144) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.BlockingSingleSubscriber.onSubscribe(BlockingSingleSubscriber.java:54) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onSubscribe(FluxPeekFuseable.java:178) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:55) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribe(Mono.java:4576) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.block(Mono.java:1778) ~[reactor-core-3.7.5.jar:3.7.5]
at io.modelcontextprotocol.server.transport.WebMvcSseServerTransport.handleMessage(WebMvcSseServerTransport.java:263) ~[mcp-spring-webmvc-0.7.0.jar:0.7.0]
at org.springframework.web.servlet.function.support.HandlerFunctionAdapter.handle(HandlerFunctionAdapter.java:108) ~[spring-webmvc-6.2.6.jar:6.2.6]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1089) ~[spring-webmvc-6.2.6.jar:6.2.6]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:979) ~[spring-webmvc-6.2.6.jar:6.2.6]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1014) ~[spring-webmvc-6.2.6.jar:6.2.6]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:914) ~[spring-webmvc-6.2.6.jar:6.2.6]
at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:590) ~[tomcat-embed-core-10.1.40.jar:6.0]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:885) ~[spring-webmvc-6.2.6.jar:6.2.6]
at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:658) ~[tomcat-embed-core-10.1.40.jar:6.0]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:195) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) ~[tomcat-embed-websocket-10.1.40.jar:10.1.40]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-6.2.6.jar:6.2.6]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.2.6.jar:6.2.6]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-6.2.6.jar:6.2.6]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.2.6.jar:6.2.6]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-6.2.6.jar:6.2.6]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.2.6.jar:6.2.6]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:167) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:483) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:116) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:344) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:398) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:903) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1740) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1189) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:658) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:63) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at java.base/java.lang.Thread.run(Thread.java:1583) ~[na:na]
2025-05-07T21:33:54.040+02:00 ERROR 64151 --- [nio-8080-exec-5] o.a.c.c.C.[.[.[/].[dispatcherServlet] : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed: java.nio.BufferOverflowException] with root cause
java.nio.BufferOverflowException: null
at java.base/java.nio.HeapByteBuffer.put(HeapByteBuffer.java:238) ~[na:na]
at org.apache.catalina.connector.OutputBuffer.transfer(OutputBuffer.java:802) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.connector.OutputBuffer.append(OutputBuffer.java:670) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.connector.OutputBuffer.writeBytes(OutputBuffer.java:377) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.connector.OutputBuffer.write(OutputBuffer.java:355) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.connector.CoyoteOutputStream.write(CoyoteOutputStream.java:102) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.springframework.web.context.request.async.StandardServletAsyncWebRequest$LifecycleServletOutputStream.write(StandardServletAsyncWebRequest.java:401) ~[spring-web-6.2.6.jar:6.2.6]
at java.base/java.io.OutputStream.write(OutputStream.java:124) ~[na:na]
at org.springframework.web.servlet.function.SseServerResponse$DefaultSseBuilder.send(SseServerResponse.java:143) ~[spring-webmvc-6.2.6.jar:6.2.6]
at org.springframework.web.servlet.function.SseServerResponse$DefaultSseBuilder.writeString(SseServerResponse.java:205) ~[spring-webmvc-6.2.6.jar:6.2.6]
at org.springframework.web.servlet.function.SseServerResponse$DefaultSseBuilder.data(SseServerResponse.java:193) ~[spring-webmvc-6.2.6.jar:6.2.6]
at io.modelcontextprotocol.server.transport.WebMvcSseServerTransport.lambda$sendMessage$0(WebMvcSseServerTransport.java:181) ~[mcp-spring-webmvc-0.7.0.jar:0.7.0]
at java.base/java.util.concurrent.ConcurrentHashMap$ValuesView.forEach(ConcurrentHashMap.java:4783) ~[na:na]
at io.modelcontextprotocol.server.transport.WebMvcSseServerTransport.lambda$sendMessage$1(WebMvcSseServerTransport.java:179) ~[mcp-spring-webmvc-0.7.0.jar:0.7.0]
at reactor.core.publisher.MonoRunnable.subscribe(MonoRunnable.java:49) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribe(Mono.java:4576) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribeWith(Mono.java:4641) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribe(Mono.java:4403) ~[reactor-core-3.7.5.jar:3.7.5]
at io.modelcontextprotocol.spec.DefaultMcpSession.lambda$new$0(DefaultMcpSession.java:138) ~[mcp-0.7.0.jar:0.7.0]
at reactor.core.publisher.LambdaMonoSubscriber.onNext(LambdaMonoSubscriber.java:171) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onNext(FluxOnErrorResume.java:79) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:129) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2570) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.request(FluxMapFuseable.java:171) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.set(Operators.java:2366) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.FluxOnErrorResume$ResumeSubscriber.onSubscribe(FluxOnErrorResume.java:74) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onSubscribe(FluxMapFuseable.java:96) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:55) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.InternalMonoOperator.subscribe(InternalMonoOperator.java:76) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.MonoDefer.subscribe(MonoDefer.java:53) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribe(Mono.java:4576) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribeWith(Mono.java:4641) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribe(Mono.java:4542) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribe(Mono.java:4478) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribe(Mono.java:4450) ~[reactor-core-3.7.5.jar:3.7.5]
at io.modelcontextprotocol.spec.DefaultMcpSession.lambda$new$3(DefaultMcpSession.java:138) ~[mcp-0.7.0.jar:0.7.0]
at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onNext(FluxPeekFuseable.java:196) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Operators$ScalarSubscription.request(Operators.java:2570) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.request(FluxPeekFuseable.java:144) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.BlockingSingleSubscriber.onSubscribe(BlockingSingleSubscriber.java:54) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.FluxPeekFuseable$PeekFuseableSubscriber.onSubscribe(FluxPeekFuseable.java:178) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.MonoJust.subscribe(MonoJust.java:55) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.subscribe(Mono.java:4576) ~[reactor-core-3.7.5.jar:3.7.5]
at reactor.core.publisher.Mono.block(Mono.java:1778) ~[reactor-core-3.7.5.jar:3.7.5]
at io.modelcontextprotocol.server.transport.WebMvcSseServerTransport.handleMessage(WebMvcSseServerTransport.java:263) ~[mcp-spring-webmvc-0.7.0.jar:0.7.0]
at org.springframework.web.servlet.function.support.HandlerFunctionAdapter.handle(HandlerFunctionAdapter.java:108) ~[spring-webmvc-6.2.6.jar:6.2.6]
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1089) ~[spring-webmvc-6.2.6.jar:6.2.6]
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:979) ~[spring-webmvc-6.2.6.jar:6.2.6]
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1014) ~[spring-webmvc-6.2.6.jar:6.2.6]
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:914) ~[spring-webmvc-6.2.6.jar:6.2.6]
at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:590) ~[tomcat-embed-core-10.1.40.jar:6.0]
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:885) ~[spring-webmvc-6.2.6.jar:6.2.6]
at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:658) ~[tomcat-embed-core-10.1.40.jar:6.0]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:195) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) ~[tomcat-embed-websocket-10.1.40.jar:10.1.40]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-6.2.6.jar:6.2.6]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.2.6.jar:6.2.6]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-6.2.6.jar:6.2.6]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.2.6.jar:6.2.6]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-6.2.6.jar:6.2.6]
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:116) ~[spring-web-6.2.6.jar:6.2.6]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:167) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:483) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:116) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:344) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:398) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:903) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1740) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1189) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:658) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:63) ~[tomcat-embed-core-10.1.40.jar:10.1.40]
at java.base/java.lang.Thread.run(Thread.java:1583) ~[na:na]
2025-05-07T21:33:54.042+02:00 WARN 64151 --- [nio-8080-exec-5] .w.s.m.s.DefaultHandlerExceptionResolver : Ignoring exception, response committed already: org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class java.util.LinkedHashMap] with preset Content-Type 'text/event-stream'
2025-05-07T21:33:54.042+02:00 WARN 64151 --- [nio-8080-exec-5] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class java.util.LinkedHashMap] with preset Content-Type 'text/event-stream']
2025-05-07T21:33:54.046+02:00 ERROR 64151 --- [nio-8080-exec-8] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session a2c209b5-4f6a-4675-8c4c-39733c6b5823: Cannot invoke "org.apache.catalina.connector.OutputBuffer.isBlocking()" because "this.ob" is null
2025-05-07T21:33:54.046+02:00 ERROR 64151 --- [nio-8080-exec-8] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 1c57403f-180f-4079-a8ca-b9554aaf383a: Cannot invoke "org.apache.catalina.connector.OutputBuffer.isBlocking()" because "this.ob" is null
2025-05-07T21:33:54.047+02:00 ERROR 64151 --- [nio-8080-exec-8] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 1ac5ae28-1763-40e3-b2d5-cc4ecb765d6a: ServletOutputStream failed to flush: java.io.IOException: Broken pipe
2025-05-07T21:33:54.047+02:00 ERROR 64151 --- [nio-8080-exec-8] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 5c0cb168-06fb-4981-83f2-604789055d4a: Response not usable after response errors.
2025-05-07T21:33:54.047+02:00 ERROR 64151 --- [nio-8080-exec-8] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 5e0c7216-87ce-4dc6-a418-de8e4297f5a8: Response not usable after response errors.
2025-05-07T21:33:54.048+02:00 ERROR 64151 --- [nio-8080-exec-3] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session a2c209b5-4f6a-4675-8c4c-39733c6b5823: Cannot invoke "org.apache.catalina.connector.OutputBuffer.isBlocking()" because "this.ob" is null
2025-05-07T21:33:54.048+02:00 ERROR 64151 --- [nio-8080-exec-7] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session a2c209b5-4f6a-4675-8c4c-39733c6b5823: Cannot invoke "org.apache.catalina.connector.OutputBuffer.isBlocking()" because "this.ob" is null
2025-05-07T21:33:54.048+02:00 ERROR 64151 --- [nio-8080-exec-3] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 1c57403f-180f-4079-a8ca-b9554aaf383a: Cannot invoke "org.apache.catalina.connector.OutputBuffer.isBlocking()" because "this.ob" is null
2025-05-07T21:33:54.048+02:00 ERROR 64151 --- [nio-8080-exec-7] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 1c57403f-180f-4079-a8ca-b9554aaf383a: Cannot invoke "org.apache.catalina.connector.OutputBuffer.isBlocking()" because "this.ob" is null
2025-05-07T21:33:54.048+02:00 ERROR 64151 --- [nio-8080-exec-3] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 1ac5ae28-1763-40e3-b2d5-cc4ecb765d6a: Response not usable after response errors.
2025-05-07T21:33:54.048+02:00 ERROR 64151 --- [nio-8080-exec-7] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 1ac5ae28-1763-40e3-b2d5-cc4ecb765d6a: Response not usable after response errors.
2025-05-07T21:33:54.048+02:00 ERROR 64151 --- [nio-8080-exec-3] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 2b39475b-90f9-4e6a-b2f6-fa9f92411205: ServletOutputStream failed to flush: java.io.IOException: Broken pipe
2025-05-07T21:33:54.048+02:00 ERROR 64151 --- [nio-8080-exec-7] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 2b39475b-90f9-4e6a-b2f6-fa9f92411205: ServletOutputStream failed to flush: java.io.IOException: Broken pipe
2025-05-07T21:33:54.048+02:00 ERROR 64151 --- [nio-8080-exec-3] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 5c0cb168-06fb-4981-83f2-604789055d4a: Response not usable after response errors.
2025-05-07T21:33:54.048+02:00 ERROR 64151 --- [nio-8080-exec-7] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 5c0cb168-06fb-4981-83f2-604789055d4a: Response not usable after response errors.
2025-05-07T21:33:54.048+02:00 ERROR 64151 --- [nio-8080-exec-3] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 5e0c7216-87ce-4dc6-a418-de8e4297f5a8: Response not usable after response errors.
2025-05-07T21:33:54.048+02:00 ERROR 64151 --- [nio-8080-exec-7] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session 5e0c7216-87ce-4dc6-a418-de8e4297f5a8: Response not usable after response errors.
2025-05-07T21:33:54.048+02:00 ERROR 64151 --- [nio-8080-exec-9] i.m.s.t.WebMvcSseServerTransport : Failed to send message to session a2c209b5-4f6a-4675-8c4c-39733c6b5823: Cannot invoke "org.apache.catalina.connector.OutputBuffer.isBlocking()" because "this.ob" is null
Environment
Spring AI 1.0.0-M6, Spring Boot 3.4.5, Java 21
Steps to reproduce
Setup a Spring Boot project with Spring AI (WebMVC), implement a sample service annotated with @Tool and connect it to the Cursor AI (MCP Client)
Expected behavior
Not having error and warn logs and random disconnects.
Minimal Complete Reproducible example
https://github.com/jpomykala/spring-boot-ai-mcp-webmvc-sample
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