If you do not have access to the error logs of your server, you can display the error on the redirection page by doing the following:
- Disable the Instant Payment Notification URL at the end of the payment in Merchant Back Office.
As a reminder, deactivation is performed in Settings > Notification rules > right-clicking Instant Payment Notification URL at the end of the payment > Disable the rule.
- Open the filewp-config.phplocated in the root directory of your site.
- Replace:define( 'WP_DEBUG', false );
with:define( 'WP_DEBUG', true );
- Make a test payment and click on the return to shop button, your error should appear on the screen.
- Once the error has been identified, remember to disable DEV mode so that errors are no longer displayed, and reactivate the Instant Payment Notification URL at the end of the payment.