# E06012 — WebhookCallbackUnverified

The callback URL did not confirm that it wants to receive deliveries. The url field error names the failure as connection_refused, timeout, tls_error, http_4xx, http_5xx or challenge_failed.

- **HTTP status**: `422`
- **Type**: `validation_error`
- **Name**: `WebhookCallbackUnverified`

## What to do

The request body parsed, but one or more values are invalid. Read the `details` array: each entry names the failing field (`param`, a dotted path like `to[0].email`) with a human-readable reason. Fix the named fields and retry.

## Related

- [E06xxx — Webhooks](/docs/api/errors/E06xxx): every code in this range
- [Errors](/docs/api/errors): the full wire contract, status mapping, and error catalog
- [Error handling](/docs/guides/errors): branching on `type` and `code`, validation details, and `vendor_code`

## Related resources

- [Should I use a Bird SDK or call the API directly?](/explained/platform/should-i-use-an-sdk-or-call-the-api-directly) (answer)
- [Build your first integration](/learn/paths/integration) (course)
- [Send your first email](/docs/get-started/send-your-first-email) (docs)

[Get an implementation brief](/learn/workspace?topic=api-basics)