Symptoms:

  • With inline-payments, the buyer is redirected back to the shopping cart after clicking "Buy now".
  • No transaction is triggered and the buyer does not see an error message.
  • In the browser console an error 500 shows up.
  • In the error log of the webserver (not in the Magento log) this message is shown:
    PHP Fatal error: Can't inherit abstract function Netresearch_OPS_Helper_Payment_DirectLink...


Solution:

See FAQ article What does the error message "PHP Fatal error: Can't inherit abstract function ..." mean?