WebClient defaultStatusHandler raise a WebClientRequestException in a NONE-Web Environment

[hantsy]

My example project: https://github.com/hantsy/spring6-sandbox/tree/master/boot-http-service

• Java 21
• Spring Boot 3.5.0
• WebFlux Stack

Reproducing Steps:

1. run mvn clean compile -DskipTests in the project root folder.
2. run mvn spring-boot:run in server and client folder respectively.

You will see an exception like the following in the client console.

org.springframework.web.reactive.function.client.WebClientRequestException: 
executor not accepting a task
	
at org.springframework.web.reactive.function.client.ExchangeFunctions$DefaultExchangeFunction.lambda$wrapException$9(ExchangeFunctions.java:137) ~[spring-webflux-6.2.7.jar:6.2.7]

If I remove the spring.main.web-application-type line in the client application.properties and set up the server.port=8888, and rerun the application, the .defaultStatusHandler will raise WebClientRespoonseException.$NotFound as expected.

But the WebClient should work in a none-web application as expected.

[wilkinsona]

I'm unable to reproduce the problem by following the provided steps. Here's the client's output:

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/

 :: Spring Boot ::                (v3.5.0)

2025-05-27T07:50:42.985+01:00  INFO 22086 --- [client] [           main] c.example.demo.client.ClientApplication  : Starting ClientApplication v0.0.1-SNAPSHOT using Java 21.0.5 with PID 22086 (/Users/aw036093/dev/temp/spring6-sandbox/boot-http-service/client/target/client-0.0.1-SNAPSHOT.jar started by aw036093 in /Users/aw036093/dev/temp/spring6-sandbox/boot-http-service)
2025-05-27T07:50:42.986+01:00 DEBUG 22086 --- [client] [           main] c.example.demo.client.ClientApplication  : Running with Spring Boot v3.5.0, Spring v6.2.7
2025-05-27T07:50:42.987+01:00  INFO 22086 --- [client] [           main] c.example.demo.client.ClientApplication  : No active profile set, falling back to 1 default profile: "default"
2025-05-27T07:50:43.527+01:00 DEBUG 22086 --- [client] [           main] c.e.d.client.ClientExampleInitializer    : get all posts.
2025-05-27T07:50:43.609+01:00 ERROR 22086 --- [client] [           main] i.n.r.d.DnsServerAddressStreamProviders  : Unable to load io.netty.resolver.dns.macos.MacOSDnsServerAddressStreamProvider, fallback to system defaults. This may result in incorrect DNS resolutions on MacOS. Check whether you have a dependency on 'io.netty:netty-resolver-dns-native-macos'. Use DEBUG level to see the full stack: java.lang.UnsatisfiedLinkError: failed to load the required native library
2025-05-27T07:50:43.645+01:00 DEBUG 22086 --- [client] [           main] c.e.d.client.ClientExampleInitializer    : save post and update post
2025-05-27T07:50:43.648+01:00  INFO 22086 --- [client] [           main] reactor.Mono.FlatMap.1                   : | onSubscribe([Fuseable] MonoFlatMap.FlatMapMain)
2025-05-27T07:50:43.648+01:00  INFO 22086 --- [client] [           main] reactor.Mono.FlatMap.1                   : | request(unbounded)
2025-05-27T07:50:43.649+01:00 DEBUG 22086 --- [client] [           main] c.e.d.client.ClientExampleInitializer    : get post by id that not existed.
2025-05-27T07:50:43.673+01:00  INFO 22086 --- [client] [           main] c.example.demo.client.ClientApplication  : Started ClientApplication in 0.888 seconds (process running for 1.148)
2025-05-27T07:50:43.806+01:00  INFO 22086 --- [client] [tor-http-nio-16] reactor.Mono.FlatMap.1                   : | onNext(<201 CREATED Created,[Location:"/posts/ce7be93d-ceee-4609-8b3a-16b0868b16ce", content-length:"0"]>)
2025-05-27T07:50:43.809+01:00 DEBUG 22086 --- [client] [tor-http-nio-16] c.e.d.client.ClientExampleInitializer    : Post id: ce7be93d-ceee-4609-8b3a-16b0868b16ce
2025-05-27T07:50:43.809+01:00  INFO 22086 --- [client] [tor-http-nio-16] reactor.Mono.FlatMap.2                   : | onSubscribe([Fuseable] MonoFlatMap.FlatMapMain)
2025-05-27T07:50:43.809+01:00  INFO 22086 --- [client] [tor-http-nio-16] reactor.Mono.FlatMap.2                   : | request(unbounded)
2025-05-27T07:50:43.810+01:00  INFO 22086 --- [client] [tor-http-nio-16] reactor.Mono.FlatMap.1                   : | onComplete()
2025-05-27T07:50:43.830+01:00 ERROR 22086 --- [client] [tor-http-nio-12] c.e.d.client.ClientExampleInitializer    : error:

org.springframework.web.reactive.function.client.WebClientResponseException$InternalServerError: 500 Internal Server Error from GET http://localhost:8080/posts/a2984a20-28d3-4bce-9321-13670908819c
	at org.springframework.web.reactive.function.client.WebClientResponseException.create(WebClientResponseException.java:332) ~[spring-webflux-6.2.7.jar!/:6.2.7]
	Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
	*__checkpoint ⇢ 500 INTERNAL_SERVER_ERROR from GET http://localhost:8080/posts/a2984a20-28d3-4bce-9321-13670908819c [DefaultWebClient]
Original Stack Trace:
		at org.springframework.web.reactive.function.client.WebClientResponseException.create(WebClientResponseException.java:332) ~[spring-webflux-6.2.7.jar!/:6.2.7]
		at org.springframework.web.reactive.function.client.DefaultClientResponse.lambda$createException$1(DefaultClientResponse.java:214) ~[spring-webflux-6.2.7.jar!/:6.2.7]
		at reactor.core.publisher.FluxMap$MapSubscriber.onNext(FluxMap.java:106) ~[reactor-core-3.7.6.jar!/:3.7.6]
		at reactor.core.publisher.FluxOnErrorReturn$ReturnSubscriber.onNext(FluxOnErrorReturn.java:162) ~[reactor-core-3.7.6.jar!/:3.7.6]
		at reactor.core.publisher.FluxDefaultIfEmpty$DefaultIfEmptySubscriber.onNext(FluxDefaultIfEmpty.java:122) ~[reactor-core-3.7.6.jar!/:3.7.6]
		at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onNext(FluxMapFuseable.java:129) ~[reactor-core-3.7.6.jar!/:3.7.6]
		at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onNext(FluxContextWrite.java:107) ~[reactor-core-3.7.6.jar!/:3.7.6]
		at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onNext(FluxMapFuseable.java:299) ~[reactor-core-3.7.6.jar!/:3.7.6]
		at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onNext(FluxFilterFuseable.java:337) ~[reactor-core-3.7.6.jar!/:3.7.6]
		at reactor.core.publisher.Operators$BaseFluxToMonoOperator.completePossiblyEmpty(Operators.java:2096) ~[reactor-core-3.7.6.jar!/:3.7.6]
		at reactor.core.publisher.MonoCollect$CollectSubscriber.onComplete(MonoCollect.java:145) ~[reactor-core-3.7.6.jar!/:3.7.6]
		at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:144) ~[reactor-core-3.7.6.jar!/:3.7.6]
		at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:260) ~[reactor-core-3.7.6.jar!/:3.7.6]
		at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:144) ~[reactor-core-3.7.6.jar!/:3.7.6]
		at reactor.netty.channel.FluxReceive.onInboundComplete(FluxReceive.java:413) ~[reactor-netty-core-1.2.6.jar!/:1.2.6]
		at reactor.netty.channel.ChannelOperations.onInboundComplete(ChannelOperations.java:455) ~[reactor-netty-core-1.2.6.jar!/:1.2.6]
		at reactor.netty.channel.ChannelOperations.terminate(ChannelOperations.java:509) ~[reactor-netty-core-1.2.6.jar!/:1.2.6]
		at reactor.netty.http.client.HttpClientOperations.onInboundNext(HttpClientOperations.java:821) ~[reactor-netty-http-1.2.6.jar!/:1.2.6]
		at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:115) ~[reactor-netty-core-1.2.6.jar!/:1.2.6]
		at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:107) ~[netty-codec-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:436) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:346) ~[netty-codec-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:318) ~[netty-codec-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:251) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:442) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1357) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:868) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:796) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:732) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:658) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562) ~[netty-transport-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:998) ~[netty-common-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.121.Final.jar!/:4.1.121.Final]
		at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.121.Final.jar!/:4.1.121.Final]
		at java.base/java.lang.Thread.run(Thread.java:1583) ~[na:na]

2025-05-27T07:50:43.830+01:00 DEBUG 22086 --- [client] [tor-http-nio-15] c.e.d.client.ClientExampleInitializer    : The existing post: Post[id=a2189bf5-6dfe-4d4c-a0dd-e63284eff4ac, title=First Post, content=Content of First Post, status=DRAFT, createdAt=2025-05-27T07:50:18.075474]
2025-05-27T07:50:43.830+01:00  INFO 22086 --- [client] [tor-http-nio-16] reactor.Mono.FlatMap.2                   : | onNext(Post[id=ce7be93d-ceee-4609-8b3a-16b0868b16ce, title=test, content=test content, status=DRAFT, createdAt=2025-05-27T07:50:43.794102])
2025-05-27T07:50:43.835+01:00 DEBUG 22086 --- [client] [tor-http-nio-16] c.e.d.client.ClientExampleInitializer    : post: Post[id=ce7be93d-ceee-4609-8b3a-16b0868b16ce, title=test, content=test content, status=DRAFT, createdAt=2025-05-27T07:50:43.794102]
2025-05-27T07:50:43.835+01:00 DEBUG 22086 --- [client] [tor-http-nio-16] c.e.d.client.ClientExampleInitializer    : getting post: Post[id=ce7be93d-ceee-4609-8b3a-16b0868b16ce, title=test, content=test content, status=DRAFT, createdAt=2025-05-27T07:50:43.794102]
2025-05-27T07:50:43.835+01:00 DEBUG 22086 --- [client] [tor-http-nio-15] c.e.d.client.ClientExampleInitializer    : The existing post: Post[id=8f65ec83-75b5-4f5c-bfed-02ad72ef7413, title=Second Post, content=Content of Second Post, status=DRAFT, createdAt=2025-05-27T07:50:18.076155]
2025-05-27T07:50:43.835+01:00 DEBUG 22086 --- [client] [tor-http-nio-15] c.e.d.client.ClientExampleInitializer    : The existing post: Post[id=ce7be93d-ceee-4609-8b3a-16b0868b16ce, title=test, content=test content, status=DRAFT, createdAt=2025-05-27T07:50:43.794102]
2025-05-27T07:50:43.836+01:00  INFO 22086 --- [client] [tor-http-nio-16] reactor.Mono.FlatMap.2                   : | onComplete()
2025-05-27T07:50:43.840+01:00 DEBUG 22086 --- [client] [tor-http-nio-16] c.e.d.client.ClientExampleInitializer    : updated status: <204 NO_CONTENT No Content,[]>

[hantsy]

I used Windows 10 pro to test it, the exception is different from this org.springframework.web.reactive.function.client.WebClientResponseException$InternalServerError: 500 Internal Server Error from GET http://localhost:8080/posts/a2984a20-28d3-4bce-9321-13670908819c

1. If the client is a web application with a server port, and it worked as expected, a WebClientResponseExcpetoin indicates there is a 404 error.
2. If change the application type to none, I get the WebClientRequestException as described above.

I have added the RestExceptionHandler in the server, and in the client module, at the end of the listener method, it tried to get post by a non-existing id, which should return status 404.

[wilkinsona]

Thanks, but that doesn't help me to reproduce the described behavior.

The situation's not helped by the complexity of the sample. It seems to include quite a few things that are unrelated to WebClient's behavior. For example, the mapping to problem details does not seem to be relevant. Creating, saving, and deleting entries in a repository also seems to be unrelated from what you have described and a simple HTTP call that receives a 404 response should be sufficient.

If you would like us to spend more time investigating, please take the time to produce a sample that focuses only on the problem and contains the bare minimum of code and dependencies that is necessary to reproduce it.

[spring-projects-issues]

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