Error Failure code: 321 during payment

3D Secure is an additional security layer for online card payments (also known as "CNP" – Card Not Present transactions). It usually asks you to confirm the payment with a one-time code sent by your bank (via SMS, banking app, push notification, etc.).

This error means that the card you are trying to use does not support 3D Secure, which requires transaction confirmation via a one-time code.

Failure code: 321 (3D Secure authentication failed)

This error (321) appears when:

• your card does not support 3D Secure at all, or
• 3D Secure is disabled for your card, or
• the authentication step was not successfully completed

In any of these cases the bank simply declines the transaction.

What you can do:

• Try paying with a different card (very often this solves the issue immediately).
• Use another payment method — for example, try Visa, or any of the alternative options listed here → Available payment methods.
• Contact your bank / card issuer and ask whether it’s possible to enable 3D Secure for your card.