# WebAuthn challenge invalid

The KeenAuth APIs return this problem type with HTTP status 400 (Bad Request).

## Problem type

| Field | Value |
|---|---|
| Type URI | `https://docs.keenauth.com/errors/webauthn_challenge_invalid` |
| Code | `webauthn_challenge_invalid` |
| HTTP status | 400 Bad Request |
| Title | WebAuthn challenge invalid |

## Meaning

The ceremony challenge is unknown, expired, belongs to another transaction or was already used (single use).

## 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/webauthn_challenge_invalid",
  "title": "WebAuthn challenge invalid",
  "status": 400,
  "code": "webauthn_challenge_invalid",
  "detail": "...",
  "instance": "urn:idp:request:<request_id>"
}
```

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