If you have noticed a higher number of pending or failed transactions within WooCommerce, this is most likely caused by the customer closing the browser or moving to another website before the PostFinance system has had a chance to redirect them back the website.
Luckily this can be fixed by enabling the Direct HTTP server-to-server request in the Transaction feedback section.
The timing of the request must be set to Always deferred or Online.
Both input fields below that must be set like the following:
Finally, make sure to set the request method to POST.
If the customer clicks away, the PostFinance system will send the order data back to the website to log the correct order data.