vatverify home
Start free
All errors

invalid_format

The request body is malformed, a required field is missing, or a field has the wrong type.

HTTP 400 · Bad Request

Example response

{
  "error": {
    "code": "invalid_format",
    "message": "vat_numbers must be a non-empty array."
  },
  "meta": {
    "request_id": "a1b2c3d4-...",
    "latency_ms": 0
  }
}

What happened

The request failed schema validation before reaching any registry. Common causes: a required field is absent, a field has the wrong type (e.g. a string where an array is expected), or the JSON body is syntactically invalid.

How to fix

  1. Check the API reference for required fields on the endpoint you're calling.
  2. For GET /v1/validate, vat_number is required as a query parameter.
  3. For POST /v1/validate/batch, vat_numbers must be a non-empty array of strings.
  4. For POST /v1/decide, both seller_vat and buyer_vat are required.
  5. Verify your request includes Content-Type: application/json on POST requests.

Common mistakes

  • Sending vat_number as an array: the single-validate endpoint takes a string, not an array.
  • Omitting Content-Type: application/json on POST requests: the body is read as empty without it.
  • Sending an empty vat_numbers: [] array to the batch endpoint: minimum 1 item required.
  • Invalid JSON syntax: trailing commas, unquoted keys. Use a JSON validator before debugging the API.

Related errors