RTB API: Getting 400 INVALID_ARGUMENT Error on buyers.userLists.create

[kei]

Hello,

I'm trying to create a new user list using the Realtime Bidding API v1 but consistently receive a 400 INVALID_ARGUMENT error. I have confirmed that my Buyer Account ID is correct and my OAuth 2.0 token is valid with the https://www.googleapis.com/auth/realtime-bidding scope.

It seems I was incorrectly trying to set the name field, which I now understand is an output-only field. However, even after trying several combinations, I am still unable to create a list successfully.

Here are the details of my latest failed request:

Endpoint: POST https://realtimebidding.googleapis.com/v1/buyers/{MY_BUYER_ID}/userLists?alt=json

Request Body:

{
  "name": "1001",
  "displayName": "testUserLIst",
  "status": "OPEN",
  "membershipDurationDays": 15
}

Error Response:

{
  "error": {
    "code": 400,
    "message": "Request contains an invalid argument.",
    "status": "INVALID_ARGUMENT"
  }
}

Could someone please provide a working example of the minimal, valid JSON request body required to create a new user list? Any help would be greatly appreciated.

Thank you.

[Authorized Buyers API Forum Advisor]

Hello,

Thank you for the details shared.  

Did you confirm that there isn't a list already with the same name (1001)?   
The API is not very clear on error and in some cases duplication of Id's returns as INVALID_ARGUMENT.

Thanks in advance.

Thanks,
 

Fernando Morais Authorized Buyers API Team

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[2025-08-11 17:06:47Z GMT] This message is in relation to case "ref:!00D1U01174p.!500Ht01syJRp:ref" (ADR-00328974)