Thank you for your reply.
The page list several items, each with an "add to cart" button which used to redirect the user to the cart content page.
The problem now is that after the update to eCart 5, some of the buttons simply don´t work anymore. Instead of redirecting to the cart page and updating the cart content, they simply reload the current page.
Neither page nor database have been change since the upgrade.
Is there a way to completely remove the eCart functionality from the page, in order to start over with the new version?