The fix for this issue only works for Standard and Wizard templates.
The AJAX templates don't have a cart, but they are still redirected to one, which causes the error:
Files does not exist: /plugins/order/views/templates/ajax/cart.pdt on line 120 in /lib/view.php
Additionally, there is a button on the domain page (first step) for all order templates, which has a button that says something like "Skip, Order Other Items". I would think that that button should not be displayed when there are no other packages to order.
Originally reported here – http://www.blesta.com/forums/index.php?/topic/2648-sell-domains-separately-without-hosting/