Problem Details for HTTP APIs (RFC 7807) — Spring 6 support.

Spring 6 builds in ProblemDetail, a standard machine-readable error body defined by RFC 7807 (updated by RFC 9457). Instead of every service inventing its own JSON error shape, you return a application/problem+json document with a known set of fields — so clients can parse errors uniformly.

The standard shape

RFC 7807/9457 defines five members, all optional, plus arbitrary extensions:

{
  "type": "https://api.shop.com/errors/out-of-stock",
  "title": "Out of stock",
  "status": 409,
  "detail": "Product 42 has 0 units available",
  "instance": "/orders/1001",
  "productId": 42
}

type is a URI identifying the kind of error (the stable thing clients branch on), title is a short human label, status mirrors the HTTP code, detail is human-readable specifics, and instance identifies this occurrence. productId above is a custom extension.

Using it in Spring

ProblemDetail is a plain class you can return directly or build into a ResponseEntity:

@ExceptionHandler(OutOfStockException.class)
ProblemDetail handle(OutOfStockException ex) {
    ProblemDetail pd = ProblemDetail.forStatusAndDetail(
        HttpStatus.CONFLICT, ex.getMessage());
    pd.setType(URI.create("https://api.shop.com/errors/out-of-stock"));
    pd.setTitle("Out of stock");
    pd.setProperty("productId", ex.getProductId()); // extension member
    return pd;
}

The content type is automatically application/problem+json.

You also get it for free from the framework's own exceptions: extend ResponseEntityExceptionHandler (which now produces ProblemDetail bodies) or simply set:

spring.mvc.problemdetails.enabled: true   # webflux: spring.webflux.problemdetails.enabled

so built-in Spring MVC exceptions (validation failures, 404s, etc.) return RFC 7807 bodies without custom handlers.