The error message "Payment failed" shows up in the checkout.
First, check all settings in the payment provider backoffice and in Magento according to the documentation. Many times, this is just a configuration error somewhere.
If the issue persists, please take a closer look at these points:
- Are you using the most recent version of the module? If not, please update it.
- Is the API-user configured according to the documentation? Username and password must be identical in Magento and the payment provider backoffice.
- Is Alias Gateway enabled? Check this in the payment provider backoffice in "Configuration -> Account -> Your options". Alias Gateway is called "OPC" (One Page Checkout) there.
- Are the Feedback-URLs in the payment provider backoffice correct and working? See this article on how to check.
- Are the gateway-URLs in Magento filled in and correct? Note the difference between test and prod URLs.
- Are SHA-IN and SHA-OUT and the hash-algorythm configured according to the documentation? These must be identical in Magento and the payment provider backoffice.
- Check the logfile "/var/log/ops.log" and the error messages in the payment provider backoffice for more detailled error-messages.
- Check the webserver logs (Apache, nginx, etc.) and the Magento logs for errors that occur when the payment is attempted.
If the above didn't resolve the problem please check if it caused by one of the following issues: