HTTP Status 400 - Bad Request

POST /api/orders HTTP/1.1
Host: api.example.com
Content-Type: application/json

{"product_id": 42, "quantity":

HTTP/1.1 400 Bad Request
Content-Type: application/problem+json

{
  "type": "https://api.example.com/errors/malformed-json",
  "title": "Malformed JSON in request body",
  "detail": "Unexpected end of JSON input at line 1, column 35",
  "instance": "/api/orders"
}

POST /api/users HTTP/1.1
Host: api.example.com
Content-Type: application/json

{"username": "alice"}

HTTP/1.1 400 Bad Request
Content-Type: application/json

{
  "error": "validation_failed",
  "message": "Missing required field: email",
  "fields": {"email": "This field is required"}
}

GET /api/products?page=invalid&limit=-10 HTTP/1.1
Host: api.example.com

HTTP/1.1 400 Bad Request
Content-Type: application/json

{
  "error": "invalid_parameters",
  "details": [
    {"param": "page", "message": "Must be a positive integer"},
    {"param": "limit", "message": "Must be between 1 and 100"}
  ]
}