application/problem+json for every 4xx / 5xx response. The status field mirrors the HTTP status; detail is a human-readable explanation; instance is the request path. Additional members may appear depending on the error class.{
"type": "https://tools.ietf.org/html/rfc7231#section-6.5.4",
"title": "Not Found",
"status": 404,
"detail": "Customer 6e9c3b1e-… was not found.",
"instance": "/v1/customers/6e9c3b1e-…"
}