How I create an error handler (404, 500...) in Spring Boot/MVC

Additional to @Arash You could add a new BaseController class that you can extends,that handles the conversion from exception to http response.

     import com.alexfrndz.pojo.ErrorResponse;
     import com.alexfrndz.pojo.Error;
     import com.alexfrndz.pojo.exceptions.NotFoundException;
     import org.springframework.http.HttpStatus;
     import org.springframework.http.ResponseEntity;
     import org.springframework.web.bind.annotation.ExceptionHandler;
     import org.springframework.web.bind.annotation.ResponseBody;
     import org.springframework.web.bind.annotation.ResponseStatus;

     import javax.persistence.NoResultException;
     import javax.servlet.http.HttpServletRequest;
     import java.util.List;

     @Slf4j
     public class BaseController {

    @ExceptionHandler(NoResultException.class)
    public ResponseEntity<Exception> handleNoResultException(
            NoResultException nre) {
        log.error("> handleNoResultException");
        log.error("- NoResultException: ", nre);
        log.error("< handleNoResultException");
        return new ResponseEntity<Exception>(HttpStatus.NOT_FOUND);
    }


    @ExceptionHandler(Exception.class)
    public ResponseEntity<Exception> handleException(Exception e) {
        log.error("> handleException");
        log.error("- Exception: ", e);
        log.error("< handleException");
        return new ResponseEntity<Exception>(e,
                HttpStatus.INTERNAL_SERVER_ERROR);
    }

    @ExceptionHandler(NotFoundException.class)
    @ResponseStatus(value = HttpStatus.NOT_FOUND)
    @ResponseBody
    public ErrorResponse handleNotFoundError(HttpServletRequest req, NotFoundException exception) {
        List<Error> errors = Lists.newArrayList();
        errors.add(new Error(String.valueOf(exception.getCode()), exception.getMessage()));
        return new ErrorResponse(errors);
    }
   }

@ControllerAdvice
 public class ErrorHandler {

public RestErrorHandler() {
}

@ExceptionHandler(YourException.class)
@ResponseStatus(HttpStatus.BAD_REQUEST)
public XXX processException(Exception ex){}

You need a class like this. Add a method for each exception, and annotate it as you please - @ResponseBody etc.

Update for spring boot

Custom error pages

If you want to display a custom HTML error page for a given status code, you add a file to an /error folder. Error pages can either be static HTML (i.e. added under any of the static resource folders) or built using templates. The name of the file should be the exact status code or a series mask.

For example, to map 404 to a static HTML file, your folder structure would look like this

src/
 +- main/
     +- java/
     |   + <source code>
     +- resources/
         +- public/
             +- error/
             |   +- 404.html
             +- <other public assets>

Source

You may try the following code:

@ControllerAdvice
public class ExceptionController {
    @ExceptionHandler(Exception.class)
    public ModelAndView handleError(HttpServletRequest request, Exception e)   {
        Logger.getLogger(getClass().getName()).log(Level.SEVERE, "Request: " + request.getRequestURL() + " raised " + e);
        return new ModelAndView("error");
    }

    @ExceptionHandler(NoHandlerFoundException.class)
    public ModelAndView handleError404(HttpServletRequest request, Exception e)   {
        Logger.getLogger(getClass().getName()).log(Level.SEVERE, "Request: " + request.getRequestURL() + " raised " + e);
        return new ModelAndView("404");
    }
}