Error in Zuul SendErrorFilter during forward

When my Zuul Filter is unable to route to a configured URL, the 'RibbonRoutingFilter' class throws a ZuulException saying "Forwarding error" and the control goes to the 'SendErrorFilter' class.

Now when the SendErrorFilter class tries to do a forward, another exception happens during this forward call.

dispatcher.forward(ctx.getRequest(), ctx.getResponse());

The exception happening during this forward call is

Caused by: java.lang.IllegalArgumentException: UT010023: Request org.springframework.cloud.netflix.zuul.filters.pre.Servlet30WrapperFilter$Servlet30RequestWrapper@6dc974ea was not original or a wrapper
    at io.undertow.servlet.spec.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:103) ~[undertow-servlet-1.1.3.Final.jar:1.1.3.Final]
    at org.springframework.cloud.netflix.zuul.filters.post.SendErrorFilter.run(SendErrorFilter.java:74) ~[spring-cloud-netflix-core-1.0.0.RELEASE.jar:1.0.0.RELEASE]
    at com.netflix.zuul.ZuulFilter.runFilter(ZuulFilter.java:112) ~[zuul-core-1.0.28.jar:na]
    at com.netflix.zuul.FilterProcessor.processZuulFilter(FilterProcessor.java:197) ~[zuul-core-1.0.28.jar:na]

Finally when the control comes to my custom ZuulErrorFilter , i do not get the original exception. Instead the exception object i get is the one that occurs during the forward.

Update: I found that a errorPath property can be configured to point to a Error Handling Service. If it is not configured, Zuul by default looks for a service named /error and tries to dispatch to that service. Since we did not have any service for /error , the dispatcher.forward() was throwing error.

Question How can we skip this fwd to an error handling service ? We have a ErrorFilter to log the error. We do not want to have a error handling service.

Solution

We had faced the same issue and there is a simple solution to fix the Undertow "eating" the original exception, following my blog post:

http://blog.jmnarloch.io/2015/09/16/spring-cloud-zuul-error-handling/

You need to set the flag allow-non-standard-wrappers to true. In Spring Boot this is doable through registering custom UndertowDeploymentInfoCustomizer. Example:

@Bean
public UndertowEmbeddedServletContainerFactory embeddedServletContainerFactory() {
    UndertowEmbeddedServletContainerFactory factory = new UndertowEmbeddedServletContainerFactory();
    factory.addDeploymentInfoCustomizers(new UndertowDeploymentInfoCustomizer() {
        @Override
        public void customize(DeploymentInfo deploymentInfo) {
            deploymentInfo.setAllowNonStandardWrappers(true);
        }
    });
    return factory;
}

Now regarding the question, either way I would highly encourage you to implement your own ErrorController, because otherwise you may experience odd Spring Boot behaviour (in our setup - ralying on the default was always generating the Whitelabel error page with 200 HTTP status code - which never happens on Tomcat in contradiction) and in this way was not consumable by AJAX calls for instance.