Root Cause

• Invalid or expired authentication credentials: The merchant’s gateway credentials are incorrect or have expired.
• Revoked API access: The payment gateway has revoked the merchant’s authentication tokens, preventing transaction processing.
• Incorrect integration settings: The authentication details configured in the merchant’s system do not match those expected by the payment gateway.
• Gateway security updates: The payment gateway requires updated authentication protocols or methods that have not been implemented.

Troubleshooting and Solutions

• Verify and update the merchant’s authentication credentials (API keys, tokens, or login details) in the payment gateway configuration.
• If merchant’s credentials have expired or been revoked, generate new ones and update them immediately.
• Merchant shall contact the payment gateway support team to resolve any outstanding authentication issues or account restrictions.
• Retry the transaction after successfully updating and validating merchant’s authentication credentials.
• Set up proactive monitoring to receive alerts when merchant’s authentication credentials are near expiration to prevent future failures.