> For the complete documentation index, see [llms.txt](https://docs.omypayments.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.omypayments.com/api/api-endpoints/mass-payouts/error-format.md).

# Error format

On errors, the API returns a standard JSON envelope, for example:

```json
{
  "success": false,
  "message": "Missing api key",
  "statusCode": 0
}
```

Ensure you include the `apiKey` header in every request. [docs.omypayments.com](https://docs.omypayments.com/api/authentication)