I am using Paypal Canada/USA. Have you read this thread?
https://www.prestashop.com/forums/topic/328666-how-to-fix-paypal-usa-133-prestashop-1606-getting-404s-not-fulfilling-orders-on-return/
Is there a way to display the orders in the BO in more than one currency? I am using USD and CAD and would prefer to have my orders reflect the currency in which they were paid rather than have them all display in either USD or CAD.
Thanks!