Issue

When attempting to sync an audience to Facebook Custom Audiences, the Segment UI indicates that the configuration is incomplete generates a 400: Missing Audience ID error.

Product

Segment

Environment

Segment Console

Cause

This issue occurs due to one of the following reasons:

• Expired OAuth Authorization: The OAuth authorization between Segment and Facebook has expired or been revoked, preventing mappings from remaining active or configured.

• Event Tester Limitation: The Segment Event Tester does not support List destinations such as Facebook Custom Audiences. Attempting to send a test event using the Event Tester to a List destination will trigger a 400: Missing Audience ID error by default.

Resolution

Follow these steps to re-authorize your account and enable audience syncing:

1. In your Segment workspace, navigate to Destinations and select your Facebook Custom Audiences destination instance.

2. Re-authorize the OAuth connection with your Facebook account credentials.

3. Once authenticated, navigate to the Mappings tab and ensure the mapping for your audience is toggled to Enabled.