👀 Views: 18 💬 Answers: 1 📅 Created: 2025-06-09

spring-webflux exception-handling reactive-programming Java

I'm currently facing an issue with custom exception handling in a Spring WebFlux application. The goal is to return a specific JSON response when certain exceptions occur, but it seems that my global exception handler isn't always triggered correctly for all exceptions. Here's a simplified version of my exception handler: ```java import org.springframework.http.HttpStatus; import org.springframework.web.bind.annotation.ControllerAdvice; import org.springframework.web.bind.annotation.ExceptionHandler; import org.springframework.web.reactive.function.server.ServerResponse; import reactor.core.publisher.Mono; @ControllerAdvice public class GlobalExceptionHandler { @ExceptionHandler(CustomException.class) public Mono<ServerResponse> handleCustomException(CustomException ex) { return ServerResponse.status(HttpStatus.BAD_REQUEST) .bodyValue(new ErrorResponse(ex.getMessage())); } } ``` I defined a `CustomException` class that extends `RuntimeException`. However, when I throw this exception from a reactive endpoint like this: ```java @GetMapping("/test") public Mono<String> testEndpoint() { throw new CustomException("This is a custom error"); } ``` The response is sometimes a simple `500 Internal Server Error` instead of my custom error response. Additionally, I notice that if the exception is thrown during the processing of a Mono or Flux, it doesn't get caught by my global handler. I've tried using `onErrorResume` in conjunction with my services, but I want a centralized way to handle exceptions. Here’s an example of what I tried: ```java @GetMapping("/test") public Mono<String> testEndpoint() { return Mono.error(new CustomException("This is a custom error")); } ``` This approach seems to work, but it feels like I'm not leveraging the full capabilities of Spring WebFlux. Is there a better way to ensure that all exceptions are processed through my global exception handler? I also checked the Spring WebFlux version, and it’s 5.3.20. Any insights on best practices for handling exceptions in a reactive WebFlux application would be greatly appreciated!