I’m trying to programmatically create a new contact list via the Outbound API for our custom agent desktop integration. The goal is to set up a fresh list before uploading CSV data. I’m using the endpoint POST /api/v2/outbound/contactlists.
The request seems straightforward, but I keep hitting a 400 Bad Request with an INVALID_VALUE error. The error message is generic: The request contains an invalid value.. I’ve validated the JSON against the OpenAPI spec multiple times. Here is the payload I’m sending:
{
"name": "Test List - DotNet",
"description": "Automated creation test",
"type": "CALL",
"contactIds": []
}
I’ve tried removing the contactIds array entirely. I’ve tried setting type to EMAIL instead. Same result. The authentication header is valid because GET requests to /api/v2/outbound/contactlists work fine. I’m using C# with HttpClient. Is there a hidden required field in the POST body that isn’t documented? Or maybe a specific format for the name string? I’ve stripped special characters just in case. Nothing works.