You can choose when Shopify cart validation checks a rule: while a customer interacts with the cart, while they interact with Shopify checkout, or when they complete checkout. Select the steps where you want customers to see your error message.

Before you start

You need an active BlockCart subscription to save a rule. The rule's Status must be Test or Live for it to run.

Choose the steps

1. Open a checkout rule from Rules, or select Create new rule and choose Cart and checkout validation.

2. In Display, find What step will trigger this validation?

3. Select one or more steps:

   | Step | When it checks the rule | | --------------------------------- | ----------------------------------------------------------- | | Interacting with the cart | When a customer changes the cart, including adding an item. | | Interacting with the checkout | While a customer makes changes in Shopify checkout. | | Completing the checkout | When a customer tries to finish the order. |

4. Set Status to Live and select Save.

Example

This rule asks customers to add more items when their cart is below a minimum. Select Interacting with the cart if you want the error to appear when they add an item to the cart.

| Rule input | Conditions | Steps | Error message | | ------------------ | -------------------------- | ----------------------------- | --------------------------------------- | | Standard input | Cart subtotal is below $25 | Interacting with the cart | Add items to reach a $25 cart subtotal. |

Good to know

• New rules select Interacting with the checkout and Completing the checkout by default. Interacting with the cart starts off. Turn it on if you want errors during add to cart.
• Errors at Interacting with the cart show only where your theme's cart displays Shopify cart errors. Some themes and express checkout buttons skip the cart. Keep Completing the checkout selected so the rule still stops the order at Shopify checkout.
• You can select more than one step, but you must leave at least one selected to save the rule.
• These choices set when BlockCart checks the rule. Always or Only when conditions match controls whether it shows an error at a selected step.

Related articles

• Create your first checkout rule
• Always run a rule, or only when conditions match
• Write a clear error message for customers