2. Your server registers the payment with Opayo

On this page:


When your customer submits your payment form, a script on your web server constructs a Transaction Registration POST. This is sent to the Opayo Direct payment URL using HTTPS.

The Transaction Registration POST

All elements are listed in in the Transaction Registration POST section of the API Reference.

Required Values

The Transaction Registration POST must contain:

  1. Your Vendor Name assigned to you by us when we created your Opayo account.
  2. A unique payment reference for each transaction called a VendorTxCode.
  3. The payment Amount and Currency.
  4. The payment card details.
  5. The customer’s Billing and Delivery addresses.
  6. The 3D-Authentication required fields including:
    1. Browser data
    2. ThreeDSNotificationURL. This is the URL that the cardholder will return to if they are challenged.
    3. The ChallengeWindowSize specifying the size of the iframe to present on your website when the challenge window is displayed.
  7. 3D Secure reference numbers and IDs when such checks have been carried out.

Optional Values

You can also include:

  1. A description of the ordered basket, goods, or services for reporting purposes.
  2. Contact details.
  3. A flag to bypass or force transaction fraud checking.

Privacy and Security

Our Opayo Direct payment method is private because the POST is secured with 128-bit encryption between your and our servers.

  • No sensitive data is passed to the customer’s browser.
  • Anyone intercepting the POST cannot read it.

Important: When connecting to Opayo's servers, an SSL handshake will take place. Normally, this will go smoothly, but before going live with any integration, you must to check that you have the latest root certificates for Opayo's certificate issuing authority installed on your servers.You can obtain the latest root certificate from here.

Installing this certificate can differ according to your website and your hosting solution, but a good place to start is here or this site.

If you need further help configuring your SSL certification chain, you can contact opayosupport@elavon.com.


Your script sends the Transaction Registration POST in the Request object of the HTTPS POST. Our response is in the response object of the same POST.

POST Validation

When the Transaction Registration POST is received, the Opayo gateway validates that all required fields are completed and formatted correctly.

When all fields are complete, validation includes:

  • The Vendor field checked against a pre-registered set of IP addresses to ensure the POST comes from a recognised source.
  • The transaction amount for formatting.
  • The transaction currency checked against those accepted by your merchant accounts.
  • The uniqueness of the VendorTxCode to ensure it has not been used before.
  • Flag fields for content.

When you receive either a MALFORMED or INVALID message the StatusDetail field contains details to help debug your scripts.

Note: In the production environment:

  • You should inform your customer that there is a problem registering their transaction.
  • Always flag the error to your back-office systems to help debug your scripts.


If the Transaction Registration POST is incomplete, the StatusDetail field contains a MALFORMED status and details of the omissions.

Note: The MALFORMED status is often returned during early development stages when you are refining your integration.


If an invalid input is detected, the StatusDetail field contains an INVALID status with details of the problems.

When the Transaction is Registered

When your transaction is registered with the Opayo gateway, a new transaction identity code is generated called the VPSTxId. The VPSTxId is returned to you in the response part of the POST after we have requested authorisation for you.

The VPSTxId is our unique transaction reference. It is unique across all vendors using the Opayo systems and not only to you. Always include the VPSTxId in any query you send to us about a transaction so we can respond accurately.


You can email the Opayo Support team for help with your debugging issues.

Related Pages

API Reference:


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