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

# Errors and rate limits

> Handle authentication failures, missing scopes, invalid requests, and rate limits.

Scite returns JSON error responses with a `detail` field. Use the HTTP status code to decide whether to change the request, update access, or retry.

## Common errors

| Status                    | Meaning                                                                        | What to do                                                                              |
| ------------------------- | ------------------------------------------------------------------------------ | --------------------------------------------------------------------------------------- |
| `401 Unauthorized`        | The endpoint requires authentication, but the request has no valid credential. | Add or replace the `Authorization: Bearer <YOUR_API_KEY>` header.                       |
| `403 User not authorized` | The credential is valid, but the key or account lacks the required scope.      | Check the key's scopes in the API Console. If the scope isn't available, contact sales. |
| `404`                     | The requested DOI, task, collection, or other resource wasn't found.           | Check the identifier. Don't retry the same value unchanged.                             |
| `422`                     | A parameter or request body failed validation.                                 | Use the response details to correct the field name, type, or format.                    |
| `429`                     | The request exceeded a rate limit.                                             | Wait for the indicated reset, then retry with backoff.                                  |

For example, Search without a key returns:

```json theme={null}
{
  "detail": "Unauthorized"
}
```

A valid key without the required feature scope returns:

```json theme={null}
{
  "detail": "User not authorized"
}
```

## Rate limit headers

Authenticated responses expose the current short-window limit through `RateLimit-*` headers and the minute limit through `X-RateLimit-*-Minute` headers:

```text theme={null}
RateLimit-Limit: <short-window-limit>
RateLimit-Remaining: <short-window-remaining>
RateLimit-Reset: <seconds-until-reset>
X-RateLimit-Limit-Minute: <minute-limit>
X-RateLimit-Remaining-Minute: <minute-remaining>
```

Limits vary by endpoint and account. Read the headers instead of hard-coding a request rate.

## Retry safely

* Don't retry `401`, `403`, `404`, or `422` responses without changing the credential or request.
* For `429` and transient `5xx` responses, use exponential backoff with jitter.
* Honor `Retry-After` when the response includes it. Otherwise wait until the indicated rate-limit reset.
* Set a maximum retry count and an overall timeout.
* Avoid retrying write requests unless your application can prevent duplicate changes.

## Polling asynchronous tasks

Assistant and Reference Check return a task ID that you poll for results. Don't poll in a tight loop. Back off between requests, enforce an overall timeout, and preserve the exact task ID returned by the submit request.

See the [Assistant guide](/guides/assistant) and [Reference Check guide](/guides/reference-check) for their task flows.