We improved how Pressero handles out of stock in September 2021 by preventing the product from being added to the checkout page. But we are still allowing the product to be customized, which could take some time, before alerting the user that the product is out of stock.
The next improvement here is to show the out of stock error as soon as the customer enters the product page, prevent add to cart and fall back to current UX when a products inventory is depleted while a customer is customizing the product.
Instead of disallowing checkout on an item in cart that has insufficient inventory, disallow the product from being added to the shopping cart and provide feedback on the product page
When a product that uses inventory with back order disallowed, and insufficient inventory to fufill the order, is added to the shopping cart, the site user is not warned until they attempt to checkout on the shopping cart. The site user should be warned when attempting to add the product to the shopping cart, if there is insufficient inventory available.