# Errors & Limits

## Error responses

| Status | Meaning | What to do |
| --- | --- | --- |
| `401` | The API key is missing, invalid, expired, or revoked. | Create a new key in **Settings → Connected Apps** and send it as a bearer token. |
| `403` | Your account cannot use the feature or access the requested resource. | Check plan eligibility, feature allowances, and project access. |
| `404` | The project, crawl, or other resource is unavailable to this key. | Confirm the UID and list accessible projects or crawls again. |
| `409` | The resource is in a state that prevents this request. | Read the current resource state, then retry only when the operation is valid. |
| `422` | A request value, filter, or cursor is invalid. | Correct the request fields; do not alter a cursor returned by the API. |
| `429` | Too many requests were sent. | Wait for the `Retry-After` duration before retrying. |
| `503` | The service is temporarily unavailable. | Retry later with a bounded backoff. |

## Respect Retry-After

On a `429` response, wait for the number of seconds in the `Retry-After` header before sending another request. Avoid immediate retries or parallel retry bursts.

## Usage and feature allowances

Screpy evaluates account eligibility and feature allowances for each request. Before starting crawls or processing large datasets, use [account](/content/docs/api/account/index.html) to read the current plan limits, usage, and available features.

For an invalid or revoked key, return to [Authentication](/content/docs/api/authentication/index.html). If a project-specific request fails, list [projects](/content/docs/api/projects/index.html) again before retrying with a different UID.

## Pagination

List endpoints that support pagination accept `limit` and `cursor`. The default limit is `50`, and the maximum is `100`.

- Use the `next_cursor` returned by the API to request the next page.
- Treat the cursor as opaque: do not construct, edit, or reuse it for a different request.
- Stop when `next_cursor` is `null`.

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### Additional Information

[REST API Authentication](/content/docs/api/authentication/index.html)  
[Account](/content/docs/api/account/index.html)