Outbound contact list POST returns 400 INVALID_VALUE on valid JSON

Hitting a wall trying to create a new contact list via the /api/v2/outbound/contactlists endpoint. The payload is minimal, just the name and description, yet it keeps rejecting with a 400 Bad Request.

The error body is cryptic:

{
 "errors": [
 {
 "code": "INVALID_VALUE",
 "message": "Invalid value for field 'name'"
 }
 ]
}

Here’s the request body I’m sending:

{
 "name": "Test List Sydney",
 "description": "Automated test list"
}

I’ve checked the schema docs. The name field is supposed to be a simple string. I’ve tried removing the space, using underscores, and even just “Test”. Same error. The description field is optional, so that shouldn’t matter.

Curious if there’s a hidden validation rule I’m missing. The API key has full outbound permissions. I can fetch existing lists without issue. It’s just the creation that fails.

Any ideas? I’ve been staring at this for an hour and it’s driving me nuts.

The name field in that endpoint isn’t just a string, it’s a validation trap. You’re probably sending whitespace or a name that already exists in the same division, which triggers that generic INVALID_VALUE error instead of a duplicate key message. Try stripping the string and using a unique ID suffix.

{
 "name": "Campaign_Contacts_v2",
 "description": "Test list",
 "division": {
 "id": "your-division-id-here"
 }
}

Check the division ID. If you omit it, the API defaults to the global division, and if you’ve run this test before, it fails silently with 400. Also, ensure Content-Type: application/json is set explicitly. Some HTTP clients default to form-encoded, which breaks the parser.