Error handling Example with multiple errors

HTTP/1.1 400
{
    "type": "https://api.demo.nbb.be/v1/errors/validation",
    "title": "Validation errors",
    "titleKey": "errors.validation",
    "errors": [
        {
            "type": "https://api.demo.nbb.be/v1/errors/validation-user-invalid",
            "title": "Invalid user information",
            "titleKey": "errors.validation.user.invalid",
            "detail": "The start date must be before the end date",
            "detailKey": "errors.validation.user.invalid.start.date.after.end.date",
            "fields": [
                "start-date",
                "end-date"
            ],
            "identifier": "9335d74d-2649-4eec-a272-ab2803e25a40"
        },
        {
            "type": "https://api.demo.nbb.be/v1/errors/validations-user-invalid",
            "title": "Invalid user information",
            "titleKey": "errors.validation.user.invalid",
            "detail": "The username is already in use",
            "detailKey": "errors.validation.user.invalid.username.already.in.use",
            "fields": [
                "username"
            ],
            "identifier": "b9b41a65-28ed-4736-ab05-9d4defdcdd23"
        }
    ]
}

Notice in the example above that each error provides a specific identifier. This is not mandatory but can help precisely locate the source of errors.