# `INVALID_FEEDBACK_KEY` (HTTP 401): the feedback key in the webhook URL is unknown

The fb_ key in a bounce webhook URL does not exist or was rotated.

Bounce webhooks authenticate through the key embedded in their URL, since sending providers cannot add custom headers. Rotating the key on the API keys page invalidates every URL that carried the old one.

**What to do.** Generate or reveal the current key on the API keys page and update the webhook URL at your sending provider.

```json
{
    "success": false,
    "error": {
        "code": "INVALID_FEEDBACK_KEY",
        "message": "That feedback key does not exist or was rotated.",
        "request_id": "req_01m1kgdm4xngzmbmff68g94w0c"
    }
}
```

Reference: https://spaw.co/docs/errors/INVALID_FEEDBACK_KEY