> ## Documentation Index
> Fetch the complete documentation index at: https://docs.avatcado.com/llms.txt
> Use this file to discover all available pages before exploring further.

# validation_error

> Error: request body validation failed

# validation\_error

<Info>HTTP Status: **422 Unprocessable Entity**</Info>

## Example response

```json theme={null}
{
  "error": {
    "code": "validation_error",
    "message": "Invalid request body: vat_numbers must contain between 1 and 50 items",
    "docs_url": "https://docs.avatcado.com/errors/validation_error"
  },
  "meta": {
    "request_id": "550e8400-e29b-41d4-a716-446655440000"
  }
}
```

## What happened?

The request body failed schema validation. This applies to endpoints that accept a JSON body, such as the [batch validation](/batch-validation) endpoint. Common causes:

* `vat_numbers` array is empty or contains more than 50 items
* `vat_numbers` is not an array of strings
* Required fields are missing from the request body
* Extra fields with incorrect types were provided

## How to fix

1. **Check the `message` field**: It describes exactly which validation rule failed
2. **Review the request body schema**: See [Batch Validation](/batch-validation#request-body) for the expected shape
3. **Ensure correct types**: `vat_numbers` must be an array of strings, `cache` must be a boolean

```bash theme={null}
# Correct
curl -X POST https://api.avatcado.com/v1/validate/batch \
  -H "Authorization: Bearer avat_live_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{"vat_numbers": ["NL123456789B01", "DE987654321"]}'

# Wrong - empty array
curl -X POST https://api.avatcado.com/v1/validate/batch \
  -H "Authorization: Bearer avat_live_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{"vat_numbers": []}'
```

## Common mistakes

* **Sending an empty array**: `vat_numbers` must contain at least 1 item
* **Exceeding 50 items**: Split large batches into multiple requests of 50 or fewer
* **Wrong Content-Type**: Make sure you set `Content-Type: application/json`
* **Confusing with `invalid_vat_format`**: `validation_error` is about the request structure; `invalid_vat_format` is about individual VAT number formats

## Catching this error with the SDKs

<CodeGroup>
  ```typescript @avatcado/node theme={null}
  import Avatcado, { ValidationError } from '@avatcado/node';

  const avatcado = new Avatcado('avat_live_your_api_key');
  const { data, error } = await avatcado.vat.validate({ vatNumber: '...' });

  if (error instanceof ValidationError) {
    console.log(error.message);
    console.log(error.details); // Array<{ field, message }> | null
  }
  ```

  ```python Python theme={null}
  from avatcado import Avatcado, ValidationError

  avatcado = Avatcado("avat_live_your_api_key")

  try:
      result = avatcado.vat.validate("...")
  except ValidationError as e:
      print(e.message)
      print(e.details)  # list of dicts or None
  ```
</CodeGroup>

## Related errors

* [`invalid_vat_format`](/errors/invalid_vat_format) - Individual VAT number format is wrong (not the request body)
* [`invalid_json`](/errors/invalid_json) - Request body is not valid JSON at all