👀 Views: 12 💬 Answers: 1 📅 Created: 2025-06-08

spring-boot webclient exception-handling Java

I'm confused about Hey everyone, I'm running into an issue that's driving me crazy. I've been struggling with this for a few days now and could really use some help... I'm developing a REST API using Spring Boot 2.6 with Java 17, and I've encountered a peculiar issue when handling custom exceptions thrown during asynchronous calls made via WebClient. My expectation is to catch these exceptions and return a meaningful HTTP response, but it seems to be bypassing my error handling logic. I've set up a WebClient instance to make asynchronous calls to another service. Here’s a simplified version of my code: ```java @Service public class MyService { private final WebClient webClient; public MyService(WebClient.Builder webClientBuilder) { this.webClient = webClientBuilder.baseUrl("http://external-service").build(); } public Mono<MyResponse> getData() { return webClient.get() .uri("/data") .retrieve() .bodyToMono(MyResponse.class) .doOnError(MyCustomException.class, ex -> { // Custom error handling logic throw new MyCustomException("Custom error occurred", ex); }); } } ``` But when the external service returns an error (e.g., 404 or 500), my `doOnError` block isn't being triggered as expected. Instead, I'm seeing a generic `WebClientResponseException` being thrown, which isn't being caught by my application-level exception handler. Here’s the relevant part of my controller: ```java @RestController public class MyController { private final MyService myService; public MyController(MyService myService) { this.myService = myService; } @GetMapping("/fetch") public ResponseEntity<MyResponse> fetchData() { return myService.getData() .map(response -> ResponseEntity.ok(response)) .onErrorResume(MyCustomException.class, ex -> { // Handle MyCustomException return Mono.just(ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR) .body(new ErrorResponse(ex.getMessage()))); }) .block(); } } ``` I've also tried using `retry()` and `onStatus()` methods in the WebClient, but no luck. The only way I can seem to catch the error is by wrapping the entire call in a `try-catch` block, which feels like a hack. The error messages that I see in the logs seem to indicate that the error is being handled internally, and I don’t get a chance to intercept it. Any insight into how to properly catch these exceptions with the WebClient in a way that allows for clean error handling would be greatly appreciated! For context: I'm using Java on Windows. Any ideas what could be causing this? I'm working on a service that needs to handle this. My team is using Java for this REST API.