I am using Webflux and Netty in my spring boot app. RequestEntity is the request parameter in my controller class. I am getting 500 error for RequestEntity as a parameter.But this service is giving response status 200 for other inputs.

Controller class

@RestController
public class ReactiveController {

    @Autowired
    Tracer tracer;

    @GetMapping("/test")
    @ResponseBody
    public CompletableFuture<ResponseEntity<?>> test(RequestEntity<String> reqEntity,
            @RequestHeader Map<String, String> reqHeaders) {
        final CompletableFuture<ResponseEntity<?>> finalRspCompFuture = new CompletableFuture<>();
        Span span = tracer.activeSpan();
        span.setOperationName("www.google.com");
        ResponseEntity<?> rspEntity = new ResponseEntity<>(HttpStatus.OK);
        finalRspCompFuture.complete(rspEntity);
        return finalRspCompFuture;
    }
}

Expected behavior

Http Status: 200

Actual behavior

Http Status: 500(Internal server error)

Console log:

2021-07-22 09:36:27.083 ERROR 25684 --- [ctor-http-nio-4] a.w.r.e.AbstractErrorWebExceptionHandler : [de269c37-1]  500 Server Error for HTTP GET "/test"

java.lang.NullPointerException: Cannot invoke "io.opentracing.Span.setOperationName(String)" because "span" is null
    at com.example.reactiverestservice.controller.ReactiveController.test(ReactiveController.java:26) ~[main/:na]
    Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
    |_ checkpoint ? org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain]
    |_ checkpoint ? io.opentracing.contrib.spring.web.webfilter.TracingWebFilter [DefaultWebFilterChain]
    |_ checkpoint ? HTTP GET "/test" [ExceptionHandlingWebHandler]
Stack trace:
        at com.example.reactiverestservice.controller.ReactiveController.test(ReactiveController.java:26) ~[main/:na]
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:78) ~[na:na]
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
        at java.base/java.lang.reflect.Method.invoke(Method.java:567) ~[na:na]
        at org.springframework.web.reactive.result.method.InvocableHandlerMethod.lambda$invoke$0(InvocableHandlerMethod.java:146) ~[spring-webflux-5.3.4.jar:5.3.4]
        at reactor.core.publisher.MonoFlatMap$FlatMapMain.onNext(MonoFlatMap.java:125) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1815) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.MonoZip$ZipCoordinator.signal(MonoZip.java:251) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.MonoZip$ZipInner.onNext(MonoZip.java:336) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.MonoPeekTerminal$MonoTerminalPeekSubscriber.onNext(MonoPeekTerminal.java:180) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.FluxDefaultIfEmpty$DefaultIfEmptySubscriber.onNext(FluxDefaultIfEmpty.java:100) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1815) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.FluxDefaultIfEmpty$DefaultIfEmptySubscriber.onComplete(FluxDefaultIfEmpty.java:108) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:142) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.onComplete(Operators.java:2057) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.FluxMapFuseable$MapFuseableSubscriber.onComplete(FluxMapFuseable.java:150) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.FluxContextWrite$ContextWriteSubscriber.onComplete(FluxContextWrite.java:126) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.FluxMapFuseable$MapFuseableConditionalSubscriber.onComplete(FluxMapFuseable.java:344) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.FluxFilterFuseable$FilterFuseableConditionalSubscriber.onComplete(FluxFilterFuseable.java:391) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.Operators$MonoSubscriber.complete(Operators.java:1816) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.MonoCollect$CollectSubscriber.onComplete(MonoCollect.java:159) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:142) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.FluxPeek$PeekSubscriber.onComplete(FluxPeek.java:259) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.core.publisher.FluxMap$MapSubscriber.onComplete(FluxMap.java:142) ~[reactor-core-3.4.3.jar:3.4.3]
        at reactor.netty.channel.FluxReceive.onInboundComplete(FluxReceive.java:389) ~[reactor-netty-core-1.0.4.jar:1.0.4]
        at reactor.netty.channel.ChannelOperations.onInboundComplete(ChannelOperations.java:396) ~[reactor-netty-core-1.0.4.jar:1.0.4]
        at reactor.netty.http.server.HttpServerOperations.onInboundNext(HttpServerOperations.java:555) ~[reactor-netty-http-1.0.4.jar:1.0.4]
        at reactor.netty.channel.ChannelOperationsHandler.channelRead(ChannelOperationsHandler.java:94) ~[reactor-netty-core-1.0.4.jar:1.0.4]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at reactor.netty.http.server.HttpTrafficHandler.channelRead(HttpTrafficHandler.java:253) ~[reactor-netty-http-1.0.4.jar:1.0.4]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.CombinedChannelDuplexHandler$DelegatingChannelHandlerContext.fireChannelRead(CombinedChannelDuplexHandler.java:436) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:324) ~[netty-codec-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:296) ~[netty-codec-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.CombinedChannelDuplexHandler.channelRead(CombinedChannelDuplexHandler.java:251) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:719) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:655) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:581) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493) ~[netty-transport-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989) ~[netty-common-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.59.Final.jar:4.1.59.Final]
        at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.59.Final.jar:4.1.59.Final]
        at java.base/java.lang.Thread.run(Thread.java:831) ~[na:na]

Your Environment

SpringBootVersion: 2.4.3 java : 16

Source Code

reactive-rest-service.zip

Comment From: wilkinsona

Thanks for the sample but the problem you're having appears to be out of Spring Boot's control. It is tracer.activeSpan() that is returning null. tracer is an instance of io.opentracing.Tracerwhich is provided via your dependency on io.opentracing.contrib:opentracing-spring-jaeger-web-starter:2.0.3. This is a third-party project.

Comment From: techdeba901

Even if we don't use activeSpan() still we are able to see traces in Jaegar. It looks like spring webflux is automatically creating span. Is there any way to disable tracer?

Comment From: wilkinsona

Spring WebFlux doesn't do annoying with Open Tracing. I believe that is all being driven by your use of opentracing-spring-jaeger-web-starter. If you have any further questions, please follow up with them or on Stack Overflow. As I explained above, this is unrelated to Spring Boot so the Spring Boot issue tracker isn't an appropriate place for this discussion.