400 webhook_url_refused - NoResponse docs

{
  "type": "https://docs.noresponse.org/problems/webhook-url-refused",
  "title": "Webhook URL refused",
  "status": 400,
  "detail": "The URL is not a permitted webhook destination.",
  "code": "webhook_url_refused",
  "request_id": "5e8be3a91fde9499f7ce48ae66290895"
}

{
  "type": "https://docs.noresponse.org/problems/webhook-url-refused",
  "title": "Webhook URL refused",
  "status": 400,
  "detail": "The URL is not a permitted webhook destination.",
  "code": "webhook_url_refused",
  "request_id": "5e8be3a91fde9499f7ce48ae66290895"
}

HTTP 400 Not retryable

Why

The scheme is not https.
The port is not 443 or 8443.
The URL carries a user name, a password or a fragment.
The host is an IP address, not a DNS name.
The host name does not resolve.
The host name resolves to an address that is not public.

What to do

Register an https URL on port 443 or 8443. Its host name must resolve only to public addresses.

In the SDKs

The Node and Python SDKs raise BadRequestError. The Go SDK returns *apierrors.BadRequestError, which you match with errors.As.

{
  "type": "https://docs.noresponse.org/problems/webhook-url-refused",
  "title": "Webhook URL refused",
  "status": 400,
  "detail": "The URL is not a permitted webhook destination.",
  "code": "webhook_url_refused",
  "request_id": "5e8be3a91fde9499f7ce48ae66290895"
}

Every error has this shape. Errors and limits lists every code.