java - Spring ResponseStatusException does not return reason

Question

I have a very simple @RestController, and I'm trying to set a custom error message. But for some reason, the message for the error is not showing up.

This is my controller:

@RestController
@RequestMapping("openPharmacy")
public class OpenPharmacyController {


    @PostMapping
    public String findNumberOfSurgeries(@RequestBody String skuLockRequest) {
        throw new ResponseStatusException(HttpStatus.BAD_REQUEST, "This postcode is not valid");
    }

}

This is the response that I get:

{
    "timestamp": "2020-06-24T17:44:20.194+00:00",
    "status": 400,
    "error": "Bad Request",
    "message": "",
    "path": "/openPharmacy/"
}

I'm passing a JSON, but I'm not validating anything, I'm just trying to set the custom message. If I change the status code, I see that on the response, but the message is always empty.

Why is this not working like expected? This is such a simple example that I can't see what may be missing. When I debug the code I can see that the error message has all the fields set. But for some reason, the message is never set on the response.

Answer 1

This answer was provided by user Hassan in the comments on the original question. I'm only posting it as an answer to give it better visibility.

Basically, all you need to do is add server.error.include-message=always to your application.properties file, and now your message field should be populated.

This behavior was changed in Spring Boot 2.3 which you can read about here: https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-2.3-Release-Notes#changes-to-the-default-error-pages-content