Problem:
I put a product in my basket. I checked the cart, put an address and when validating the order by pressing the button "pay now", an error 500 appeared:
http://192.168.xx.xx:8069/payment/transfer/feedback
Internal Server Error
The server encountered an internal error and was unable to complete your request. Either the server is overloaded or there is an error in the application.
Solution :
use commande # apt install wkhtmltopdf
and restart server and test