Hello, My problem sound really easy but here I go. When any registered user (because only registered users can see the price and make a purchase) press the checkout button with any item on the cart and then press continue button on billing address the last button send back the customer to the cart.
Before on the 3.90 version I use paypal express for checkout instead checkout button, but on 4.0 this plugin is not supported, I upgrade my version following all steps on the attached txt, (copy setting and plugins text files).
Any Idea?