# `connection.domain_not_listed`

Action calls a connection its domain isn't listed on.

Area 11, [External services](../topics/external-services.md); not declinable; the next step is usually the human's.

> Only the actions of the domains a connection's
> `domains:` lists call it (question 18).

A connection lists the domains that call it, so a new caller is a change
a reviewer sees:









```jadpo
use app { couriers }
use shared/providers/acme_couriers

/// Where a customer's parcel is.
action track_parcel(lookup: AcmeCouriers.ParcelLookup) -> AcmeCouriers.Parcel {
    return couriers.parcels.get(lookup)
}
```

```text
error: `support` calls `couriers`, whose `domains:` doesn't list it
 --> domains/support/actions/track_parcel.jadpo:6:12
  |
6 |     return couriers.parcels.get(lookup)
  |            ^^^^^^^^^^^^^^^^^^^^ not a listed domain
  reason: A connection lists the domains whose actions may call it, so a new caller is a one-line change a reviewer sees; `couriers` lists `shipping`, and other domains go through their public actions.
  next: Add `support` to `couriers`'s `domains:` in `app.jadpo`, or call one of `shipping`'s public actions instead (human)
  rule: connection.domain_not_listed
  help: https://jadpo.dev/docs/errors/connection.domain_not_listed

check failed: 1 error, 9 files
```