Ambiguous @ExceptionHandler method mapped for [class org.springframework.web.bind.MethodArgumentNotValidException]

Springs ResponseEntityExceptionHandler has a method handleException which is annotated with :

@ExceptionHandler({     
        ...
        MethodArgumentNotValidException.class,
        ... 
    })

Your method handleMethodArgumentNotValidException is also annotated to handle MethodArgumentNotValidException. So spring finds two methods that should be used to handle the same exception, that is the reason for the exception.

**Solution ** Do not add a new method handleMethodArgumentNotValidException instead just override the method ResponseEntityExceptionHandler.handleMethodArgumentNotValid , and do not annotate it. Your class ErrorWrapper must extend ResponseEntity for that.

Try to override the method handleMethodArgumentNotValid, In my case the method become like this:

  @Override
  protected ResponseEntity<Object> handleMethodArgumentNotValid(MethodArgumentNotValidException ex,
                                                                HttpHeaders headers, HttpStatus status,
                                                                WebRequest request) {
    String errorMessage = ex.getBindingResult().getFieldErrors().stream()
                 .map(DefaultMessageSourceResolvable::getDefaultMessage)
                 .findFirst()
                 .orElse(ex.getMessage());
    return response(ex, request, HttpStatus.BAD_REQUEST, errorMessage);
  }

  private ResponseEntity<Object> response(Exception ex, WebRequest request, HttpStatus status,
                                          String message) {
    return handleExceptionInternal(ex, message, header(), status, request);
  }

Handel Exception

@ControllerAdvice
@RestController
@Slf4j
public class ExceptionHandler extends ResponseEntityExceptionHandler {
    @Override
    protected ResponseEntity<Object> handleMethodArgumentNotValid(MethodArgumentNotValidException ex, HttpHeaders headers, HttpStatus status, WebRequest request) {
        List<String> errorList = ex
                .getBindingResult()
                .getFieldErrors()
                .stream()
                .map(fieldError -> fieldError.getDefaultMessage())
                .collect(Collectors.toList());
        ErrorDetails errorDetails = new ErrorDetails(HttpStatus.BAD_REQUEST, ex.getLocalizedMessage(), errorList);
        return handleExceptionInternal(ex, errorDetails, headers, errorDetails.getStatus(), request);
    }
}
        }

Customize Error Message

@Data
public class ErrorDetails {
    private HttpStatus status;
    private String message;
    private List<String> errors;

    public ErrorDetails(HttpStatus status, String message, List<String> errors) {
        super();
        this.status = status;
        this.message = message;
        this.errors = errors;
    }

    public ErrorDetails(HttpStatus status, String message, String error) {
        super();
        this.status = status;
        this.message = message;
        errors = Arrays.asList(error);
    }
}

Sample Response

  {
      "status": "BAD_REQUEST",
      "message": "Validation failed for argument [0] in public void com.ns.hospitalmanagement.resource.PatientResource.createPatient(com.ns.hospitalmanagement.entity.Patient) with 2 errors: [Field error in object 'patient' on field 'name': rejected value [null]; codes [NotNull.patient.name,NotNull.name,NotNull.java.lang.String,NotNull]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [patient.name,name]; arguments []; default message [name]]; default message [Name Can not be Null]] [Field error in object 'patient' on field 'name': rejected value [null]; codes [NotEmpty.patient.name,NotEmpty.name,NotEmpty.java.lang.String,NotEmpty]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [patient.name,name]; arguments []; default message [name]]; default message [Name Can not be Empty]] ",
      "errors": [
        "Name Can not be Null",
        "Name Can not be Empty"
      ]
    }