The banner creative dimensions must match an offered fixed format.

What it means

The banner creative dimensions must match an offered fixed format. This check applies to the selected vendor contract and integration direction.

Why it matters

The declared profile checks the published partner contract alongside canonical OpenRTB. It does not verify runtime approval or account configuration.

How to fix it

Use an option offered by the matching request. Check the request and response together at the reported path.

Example that trips it

Request:
{
  "id": "req",
  "tmax": 200,
  "ext": {},
  "device": {},
  "imp": [
    {
      "id": "1",
      "secure": 1,
      "banner": {
        "w": 320,
        "h": 50,
        "topframe": 0,
        "format": [
          {
            "w": 320,
            "h": 50
          },
          {
            "w": 300,
            "h": 250
          }
        ]
      }
    }
  ]
}

Response:
{
  "id": "req",
  "seatbid": [
    {
      "seat": "buyer",
      "bid": [
        {
          "id": "bid",
          "impid": "1",
          "price": 1.2,
          "mtype": 1,
          "w": 728,
          "h": 90,
          "adomain": [
            "advertiser.example"
          ],
          "adm": "<div>Banner</div>"
        }
      ]
    }
  ]
}

Profile index-exchange, OpenRTB 2.6-202606. The fixture asserts openrtb.profile.index.banner_size_unoffered at seatbid[0].bid[0].w.

Check your payload

Paste a bid request or response into the tester to see whether this code fires against it, or gate on the id in CI with the CLI: the id is stable, wording is not.

• Primary protocol documentation
• Replayable source fixture

Back to the full diagnostic code reference.