Error Responses

See equivalent in the Servlet stack

You can return ProblemDetail or ErrorResponse from any @ExceptionHandler or from any @RequestMapping method to render an RFC 9457 response. This is processed as follows:

To enable RFC 9457 responses for Spring WebFlux exceptions and for any ErrorResponseException, extend ResponseEntityExceptionHandler and declare it as an @ControllerAdvice in Spring configuration. The handler has an @ExceptionHandler method that handles any ErrorResponse exception, which includes all built-in web exceptions. You can add more exception handling methods, and use a protected method to map any exception to a ProblemDetail.

You can register ErrorResponse interceptors through the WebFlux Config with a WebFluxConfigurer. Use that to intercept any RFC 9457 response and take some action.

See equivalent in the Servlet stack

You can extend an RFC 9457 response with non-standard fields in one of two ways.

One, insert into the "properties" Map of ProblemDetail. When using the Jackson library, the Spring Framework registers ProblemDetailJacksonMixin that ensures this "properties" Map is unwrapped and rendered as top level JSON properties in the response, and likewise any unknown property during deserialization is inserted into this Map.

You can also extend ProblemDetail to add dedicated non-standard properties. The copy constructor in ProblemDetail allows a subclass to make it easy to be created from an existing ProblemDetail. This could be done centrally, for example, from an @ControllerAdvice such as ResponseEntityExceptionHandler that re-creates the ProblemDetail of an exception into a subclass with the additional non-standard fields.

See equivalent in the Servlet stack

It is a common requirement to customize and internationalize error response details. It is also good practice to customize the problem details for Spring WebFlux exceptions to avoid revealing implementation details. This section describes the support for that.

An ErrorResponse exposes message codes for "type", "title", and "detail", as well as message code arguments for the "detail" field. ResponseEntityExceptionHandler resolves these through a MessageSource and updates the corresponding ProblemDetail fields accordingly.

The default strategy for message codes follows the pattern:

problemDetail.[type|title|detail].[fully qualified exception class name]

An ErrorResponse may expose more than one message code, typically adding a suffix to the default message code. The table below lists message codes, and arguments for Spring WebFlux exceptions:

See equivalent in the Servlet stack

A client application can catch WebClientResponseException, when using the WebClient, or RestClientResponseException when using the RestTemplate, and use their getResponseBodyAs methods to decode the error response body to any target type such as ProblemDetail, or a subclass of ProblemDetail.