Outbound Campaign API 422 Unprocessable Entity on Contact List Upload

General Discussion
1

Can’t get this config to load properly for the bulk contact upload process within our AppFoundry integration. We are attempting to synchronize contact lists from our external CRM to Genesys Cloud via the /api/v2/outbound/contactlists/{contactListId}/contacts endpoint. The request consistently returns a 422 Unprocessable Entity error with the following payload:

{
 "status": 422,
 "statusCode": "UNPROCESSABLE_ENTITY",
 "message": "One or more fields are invalid. Check the validation errors for details.",
 "errors": [
 {
 "field": "phone",
 "message": "Invalid phone number format. Must be E.164 compliant."
 }
 ]
}

This is perplexing because the phone numbers in the payload are strictly formatted in E.164 (e.g., +14155552671). The integration uses the standard OAuth2 service account flow with outbound:contact:write and outbound:contactlist:write scopes. The environment is mygenesys.com (US East), and we are using the latest Python SDK version 2.15.4. The issue appears only when the batch size exceeds 500 records; smaller batches upload without issue. This suggests a potential validation timeout or a hidden rate-limiting behavior on the outbound API that isn’t documented in the standard rate limit sections.

We have verified the following:

  • Validated every phone number against an independent E.164 regex validator before sending the payload. The data is clean, and manual uploads of the same records via the Genesys Cloud UI succeed without error.
  • Reduced the batch size to 100 records per request, which resolves the issue, but this severely impacts our synchronization performance for large datasets (10k+ records). We need a solution that supports larger batches without manual chunking logic in our application layer.

Is there a known limitation or a specific header required for bulk outbound contact uploads that bypasses this strict validation? We are looking to optimize the sync process for our premium app clients.

2

If I remember correctly, this specific 422 error often stems from data type mismatches in the custom attributes rather than authentication issues. When bulk uploading via the outbound API, Genesys validates the schema strictly against the contact list definition.

The JSON payload usually fails if a custom attribute defined as a string contains null values or if numeric fields receive string inputs. Check your CRM export logic to ensure all custom attributes map correctly to their expected types. For example, if custom_attribute_1 is defined as a number, sending an empty string instead of null or a valid integer triggers the unprocessable entity response.

Additionally, verify that the external_id is unique across the entire payload. Duplicate IDs in a single batch request will cause the whole operation to fail with a 422. Try isolating a small subset of records (5-10 contacts) and logging the exact JSON body sent to the endpoint. This usually reveals hidden formatting errors like trailing commas or incorrect nesting that are not apparent in larger datasets.

3

Yep, this is a known issue…

The 422 error usually stems from schema mismatches in custom attributes. Ensure null values are excluded from string fields and numeric fields do not receive string inputs during the CRM export.