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

# Deprecation

> How Arcus deprecates API features, what the Sunset header means, and how to migrate before end-of-life.

## Deprecation policy

Arcus gives developers **at least 12 months notice** before removing any endpoint, field, or behavior. The deprecation lifecycle has three stages:

| Stage         | Action                                                                                 |
| ------------- | -------------------------------------------------------------------------------------- |
| **Announced** | Listed in the changelog + deprecation table below; `Deprecation` response header added |
| **Sunset**    | `Sunset` response header added with the removal date                                   |
| **Removed**   | Feature removed; requests to removed endpoints return `410 Gone`                       |

## Response headers

When you call a deprecated endpoint or use a deprecated parameter, the response includes:

```
Deprecation: true
Sunset: Sat, 01 May 2027 00:00:00 GMT
Link: <https://arcuserp.mintlify.app/concepts/deprecation#migration-guides>; rel="deprecation"
```

Set up alerting in your HTTP client to watch for these headers so deprecations surface before they become incidents.

## Detecting deprecation headers

<CodeGroup>
  ```javascript Node theme={null}
  const response = await arcus.orders.list();

  if (response.headers?.deprecation) {
    console.warn('WARNING: This endpoint is deprecated. Sunset:', response.headers?.sunset);
  }
  ```

  ```python Python theme={null}
  response = arcus.orders.list()

  if 'deprecation' in response.raw_response.headers:
      import warnings
      warnings.warn(
          f"Deprecated endpoint. Sunset: {response.raw_response.headers.get('sunset')}",
          DeprecationWarning,
      )
  ```

  ```go Go theme={null}
  resp, err := client.Orders.ListRaw(ctx, nil)
  if resp.Header.Get("Deprecation") != "" {
      log.Printf("WARNING: deprecated endpoint. Sunset: %s", resp.Header.Get("Sunset"))
  }
  ```
</CodeGroup>

## Current deprecations

No active deprecations. This table will be updated when the first deprecated feature is announced.

| Feature | Deprecated | Sunset | Replacement |
| ------- | ---------- | ------ | ----------- |
| (none)  |            |        |             |

## Migration guides

When a significant deprecation is announced, a migration guide will be added to the [Guides](/guides/error-handling) section with step-by-step instructions for updating your integration.

## Questions?

If a deprecation would break your integration and the timeline is too short, contact support via the in-app Help button with your use case. Arcus may be able to provide an extended sunset window for documented migration blockers.