All Worldpay codes
WORLDPAY · REFUSAL CODE

Worldpay
661

Setting error in the "Terminal Processing Serial Number" message element.

Worldpay saysIntegration issue
661

Setting error in the "Terminal Processing Serial Number" message element.

What it means

Invalid request data

A field in the request has a wrong value or format.

What to do

Compare the request with the provider's API reference. The response detail usually names the field.

Don't retry as-isWho can fix it: You, the merchant
Yuno response codeINVALID_PARAMETERS
Source:Worldpay docs — Refusal response codes (Access Worldpay)

Other Worldpay codes with the same meaning

30442448590592593594595596597598599

Reference only. Codes and descriptions come from each provider's public documentation. The Yuno response code is a reference mapping and does not guarantee how a specific transaction is processed.