# E04018 — AudienceEmpty

This audience has nobody to send to. It is either empty, or none of its contacts has an email address.

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

## What to do

Add contacts that have an email address, or set an address on the contacts already in the audience, then send the broadcast again.

Operations that resolve this:

- [List contacts](/docs/api/reference/list-contacts)
- [Assign contacts to an audience](/docs/api/reference/assign-audience-contacts)
- [Update a contact](/docs/api/reference/update-contact)

## Related

- [E04xxx — Email sending & delivery](/docs/api/errors/E04xxx): 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)