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

# API Errors

> Common error responses and status codes from the lemlist API and how to handle them.

## HTTP Status Codes

The lemlist API uses standard HTTP status codes to indicate the success or failure of requests:

| Status Code | Meaning                                                               |
| ----------- | --------------------------------------------------------------------- |
| `200`       | **Success** - The request was successful                              |
| `400`       | **Bad Request** - Invalid parameters or invalid team                  |
| `401`       | **Unauthorized** - Authentication is missing or invalid               |
| `403`       | **Forbidden** - User is blocked                                       |
| `404`       | **Not Found** - Resource does not exist                               |
| `405`       | **Method Not Allowed** - HTTP method is not allowed for this endpoint |
| `429`       | **Too Many Requests** - Rate limit exceeded                           |
| `500`       | **Internal Server Error** - An error occurred on the server           |

<Note>
  For authentication related errors, refer to the <a href="/api-reference/getting-started/authentication">Authentication</a> section.
</Note>

## Common error messages

<AccordionGroup>
  <Accordion title="Bad team">
    This indicates that the team associated with your API key is invalid or you don't have permission to access the requested resource.

    <b>Common causes</b>

    <ul>
      <li>The resource belongs to a different team</li>
      <li>Your API key doesn't have access to the requested team</li>
      <li>Invalid team configuration</li>
    </ul>
  </Accordion>

  <Accordion title="Bad params">
    One or more request parameters are invalid.

    <b>Common causes</b>

    <ul>
      <li>Missing required parameters</li>
      <li>Invalid parameter format</li>
      <li>Parameter values out of acceptable range</li>
      <li>Invalid JSON in request body</li>
    </ul>

    <b>How to fix</b>: Review the endpoint documentation and ensure all required parameters are provided with correct formatting.
  </Accordion>

  <Accordion title="Bad request">
    A generic error indicating that the request could not be processed due to client error.

    <b>Common causes</b>

    <ul>
      <li>Malformed JSON</li>
      <li>Invalid data types</li>
      <li>Logical errors in request data</li>
    </ul>
  </Accordion>
</AccordionGroup>

## Best practices

<Accordion title="Recommendations">
  <ol>
    <li><b>Always check the response status code</b> before processing the response body</li>
    <li><b>Implement exponential backoff</b> for retrying failed requests</li>
    <li><b>Log error responses</b> for debugging and monitoring</li>
    <li><b>Handle authentication errors</b> by refreshing or validating your API key — see <a href="/api-reference/getting-started/authentication">how to authenticate</a></li>
    <li><b>Respect rate limits</b> by implementing request throttling — see <a href="/api-reference/getting-started/rate-limits">how to handle rate limits</a></li>
    <li><b>Validate input</b> before sending requests to avoid unnecessary API calls</li>
  </ol>
</Accordion>

## Getting help

<Accordion title="If you need assistance">
  If you encounter errors that are not documented here or need assistance:

  <ol>
    <li>Review the endpoint-specific documentation</li>
    <li>Make sure you understood how <a href="/api-reference/getting-started/authentication">to authenticate</a> works</li>
    <li><a href="https://lemlist.typeform.com/to/mfVlkyGf" target="_blank" rel="noreferrer">Contact lemlist support through the feedback form</a></li>
  </ol>
</Accordion>