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# Errors in Fern Definition

> Add errors representing failed responses from API endpoints in Fern Definition.

Fern Definition isn't recommended for new customers and Fern isn't accepting feature requests for this format. It remains supported for existing users.

Errors represent failed (non-200) responses from endpoints.

An error has:

* An HTTP status code
* A body type *(Optional)*

#### user.yml

```yaml
errors:
  UserNotFoundError:
    status-code: 404
    type: UserNotFoundErrorBody

types:
  UserNotFoundErrorBody:
    properties:
      requestedUserId: string
```

> Add errors representing failed responses from API endpoints in Fern Definition.