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

# unsupported_api_version

> HTTP 400 / 410 — the Agnes-Version header is older than the minimum supported version.

|                 |                                                  |
| --------------- | ------------------------------------------------ |
| **HTTP status** | `400 Bad Request` or `410 Gone`                  |
| **Code**        | `unsupported_api_version`                        |
| **Retry?**      | No — upgrade your client or pin a newer version. |

## When this happens

You set the `Agnes-Version` header to a date that is older than the
server's current minimum supported version. The server cannot reliably
honour the old contract and refuses the request rather than guess.

## Example response

```json theme={null}
{
  "detail": "Agnes-Version 2024-11-01 is no longer supported. Minimum supported version: 2026-01-01.",
  "code": "unsupported_api_version",
  "request_id": "5b3f6c7e-7d24-4d40-9b12-3a59c01c6e91",
  "doc_url": "https://docs.lasscyber.com/errors/unsupported_api_version"
}
```

## How to fix

* **If you pinned the version yourself**: bump the `Agnes-Version`
  value to a more recent date. The current date version is in the
  OpenAPI document
  ([`sdk/openapi/openapi.json`](https://github.com/lasscyber/agnes-docs/tree/main/policy-fixtures))
  and is `2026-04-16` at the time of writing.
* **If your SDK is pinning it**: upgrade to the latest minor of the
  SDK. See [Versioning](/sdks/versioning).
* **If you have not pinned it**: this should never happen — the API
  defaults to the latest version when no header is sent. If you see
  this without a pin, file a ticket with the `request_id`.

## Deprecation timeline

The minimum supported version moves forward roughly **once a year**.
Deprecation notices ship in the SDK CHANGELOG and the API release
notes; you have at least **six months** of warning before a date
version is removed.

## SDK behaviour

| SDK        | Exception                                                          |
| ---------- | ------------------------------------------------------------------ |
| Python     | `agnes.ValidationError` (with `code == "unsupported_api_version"`) |
| TypeScript | `ValidationError` (with `code === "unsupported_api_version"`)      |

SDKs do not retry — the only recovery is to bump the version.

## Related

* [Authentication](/get-started/authentication#pinning-the-api-contract-version)
* [Versioning](/sdks/versioning)