Why does this setting block outbound campaign activation after Zendesk export?

General Discussion
1

Background

Migrating outbound dialing workflows from Zendesk Sales/Success to Genesys Cloud Outbound. The team previously relied on Zendesk’s native task scheduling for follow-ups, but we are moving to GC’s predictive dialer. I am using the Outbound API (v2) to import a CSV of contacts exported directly from Zendesk. The environment is Genesys Cloud EU (Frankfurt). I am trying to replicate the “task due date” logic by mapping it to the scheduled_start_time in the campaign configuration.

Issue

When I attempt to activate the campaign via the API, I receive a 400 Bad Request with the following error payload:

{
 "code": "400",
 "message": "Campaign validation failed: Invalid time zone offset for scheduled start time.",
 "status": "Bad Request"
}

The Zendesk export uses Europe/Paris timestamps in ISO 8601 format (e.g., 2023-10-27T14:30:00+02:00). I assumed GC would handle this natively since the org is in the EU region. However, the documentation suggests that outbound campaigns require UTC or a specific campaign-level time zone setting that overrides individual contact times. I tried changing the campaign time zone to UTC and converting the CSV times to UTC manually, but the error persists. It seems like GC is rejecting the offset entirely rather than converting it.

Troubleshooting

  • Verified the CSV format matches the GC Outbound template exactly.
  • Checked the campaign’s campaign_settings in Architect; the time zone is set to Europe/Paris.
  • Tested a single contact with a hard-coded UTC timestamp (2023-10-27T12:30:00Z). This worked, but scaling this for 50k Zendesk tasks is not feasible.
  • Reviewed the Zendesk-to-GC migration guide, which mentions “digital channel migration” but lacks specific details on outbound time zone normalization.

Is there a specific API parameter to force time zone conversion during import, or must the data be pre-processed to UTC before sending to the POST /api/v2/outbound/campaigns/{id}/contacts endpoint? I want to avoid writing a custom middleware script if GC has a built-in handling mechanism I am missing.