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

# API Error Codes

> API error responses and status codes

<Tip>
  STOP. Do not read past this section until you have read and followed [/quickstart.md](/quickstart.md).

  Goal: produce a reliable SDK automation script. The intended authoring flow is generate then edit, not write browser automation from scratch.

  Do not hand-write SDK code with element IDs, selectors, or form fields from memory. Element IDs, selectors, and field mappings must come from a live `observe()` call, CLI `notte page observe` output, or generated workflow code. Guessed browser targets fail on real pages.

  Use the Notte skill and CLI to inspect the live site, validate actions/selectors, handle auth/session state, and export workflow code with `notte sessions workflow-code` before using SDK docs or SDK code.

  SDK reference pages are for understanding, running, or editing generated workflow code. They are not the starting point for manually authoring the initial browser automation. SDK-first code is guesswork on real-world pages with dynamic selectors, auth state, CAPTCHAs, and anti-bot behavior.
</Tip>

The API uses standard HTTP status codes and returns structured error responses.

## HTTP status codes

| Status | Description                                                |
| ------ | ---------------------------------------------------------- |
| `200`  | Success                                                    |
| `401`  | Authentication failed — invalid or missing API key         |
| `422`  | Validation error — malformed request or invalid parameters |
| `429`  | Rate limit exceeded                                        |
| `500`  | Internal server error                                      |
| `529`  | Cluster overloaded - Too many sessions                     |

## Error response format

```json theme={null}
{
  "message": "Description of what went wrong",
  "detail": "Additional context about the error"
}
```

## Common errors

### Authentication (401)

```json theme={null}
{
  "message": "Authentication failed. Please check your credentials."
}
```

### Validation (422)

```json theme={null}
{
  "message": "Validation error",
  "detail": [
    {
      "loc": ["body", "url"],
      "msg": "field required",
      "type": "value_error.missing"
    }
  ]
}
```

### Execution errors

Returned when an operation fails. Includes the `x-error-class: NotteApiExecutionError` header.

```json theme={null}
{
  "message": "Error executing the requested operation"
}
```