# Challenge required

The KeenAuth APIs return this problem type with HTTP status 428 (Precondition Required).

## Problem type

| Field | Value |
|---|---|
| Type URI | `https://docs.keenauth.com/errors/challenge_required` |
| Code | `challenge_required` |
| HTTP status | 428 Precondition Required |
| Title | Challenge required |

## Meaning

The credential step does not proceed until the bot challenge (ALTCHA) is solved; see the `challenge` extension.

## Extension members

The response body carries these additional members:

- `challenge`

## Example response

Example response body. `detail` is a human-readable English description that is not meant for end users; `instance` identifies the request.

```json
{
  "type": "https://docs.keenauth.com/errors/challenge_required",
  "title": "Challenge required",
  "status": 428,
  "code": "challenge_required",
  "detail": "...",
  "instance": "urn:idp:request:<request_id>",
  "challenge": "..."
}
```

All error codes: [Error reference](/docs/errors).