Root Cause

• Incorrect ZIP/postal code: The customer provided a ZIP or postal code that does not match the billing address on file with their card issuer.
• AVS mismatch: The payment gateway detected a mismatch during the address verification process.
• Outdated billing address: The customer recently changed their address but has not updated it with their bank or card issuer.
• Formatting errors: The ZIP/postal code was entered in an incorrect format (e.g., missing characters or incorrect country-specific formatting).

Troubleshooting and Solutions

• Ask the customer to verify and re-enter the correct ZIP/postal code associated with the billing address registered with the card issuer.
• Recommend the customer update the billing address with the bank if it has changed recently.
• Ensure the ZIP/postal code is entered in the correct format based on the selected country.
• Display clear and helpful error messages on the payment form to guide users to enter the right ZIP/postal code.
• Retry the transaction after correcting the ZIP/postal code.
• If the issue persists, work with your payment gateway to revisit the AVS rules and relax the validations if needed.