Block checkout for mixed carts (Timesact Cart Validation)

Block checkout stops a shopper from completing checkout while their cart holds both pre-order items and in-stock items, so pre-orders and in-stock items arrive as separate orders. It runs through a Shopify checkout rule called Timesact Cart Validation, which also covers Shop Pay, Apple Pay, Google Pay and other express checkouts. You turn it on per Customer Experience (the reusable template that holds your pre-order settings) in Timesact → Experiences → your Customer Experience → Storefront → Cart page → Mixed cart checkout, next to the optional cart alert pop-ups.

Plan: Block checkout: PRO. Cart alert pop-ups: all plans · Where: Timesact → Experiences → your Customer Experience → Storefront → Cart page → Pre-order tab → Mixed cart checkout

Before you start

• Your store is on a PRO plan (PRO Flexible or PRO Fixed). On other plans the Block checkout section shows a PRO badge and its switch can't be turned on.
• The Customer Experience has Pre-order turned on. Cart page settings are available for Pre-order only.
• You have access to Settings in your Shopify admin, because the checkout rule is turned on there.

How to block checkout for mixed carts

Block checkout takes two places: the checkout rule in Shopify, then the setting in your Customer Experience. Do them in this order, because Timesact sends your Block checkout settings to the rule each time you save the Customer Experience.

Step 1: Turn on the checkout rule in Shopify

1. In your Shopify admin, go to Settings → Checkout.
2. Scroll to the Checkout rules section.
3. Find Timesact Cart Validation and turn it on.
4. If Timesact Cart Validation isn't listed, click Add rule, select Timesact Cart Validation, click Save, then turn it on.

Step 2: Turn on Block checkout in Timesact

1. In Timesact, open Experiences and click the Customer Experience that runs your pre-orders.
2. Under Storefront, click Cart page.
3. On the Pre-order tab, open Mixed cart checkout.
4. In the Block checkout section, turn on Block checkout when cart mixes pre-order and in-stock items.
5. Under Checkout error message, edit the Message. This is the text shoppers see when checkout is blocked. The default is "Your cart contains both pre-order and in-stock items. Please remove one type before checking out."
6. Click Save. Timesact shows "Customer Experience saved", and your settings are now in the Timesact Cart Validation rule.

Repeat Step 2 in every Customer Experience whose pre-orders you want kept apart from in-stock items. Each Customer Experience carries its own Block checkout switch and its own message.

What happens next

Once Block checkout is on and saved, Shopify checks every cart at checkout:

• A cart with at least one pre-order item from a Customer Experience with Block checkout on, plus at least one other item, can't complete checkout. The shopper sees your Checkout error message and removes one type of item to continue.
• A cart with only pre-order items checks out normally, including pre-order items from several Customer Experiences that all have Block checkout on.
• A cart with only in-stock items checks out normally.
• The check applies to the normal checkout and to express checkouts such as Shop Pay, Apple Pay and Google Pay.

No order is created while checkout is blocked, so nothing is tagged and no email is sent. When the shopper checks out a pre-order-only cart, the order gets the Pre-order tag as usual.

Turn Block checkout off

To stop blocking mixed carts for one Customer Experience, open it → Cart page → Mixed cart checkout, turn off Block checkout when cart mixes pre-order and in-stock items and click Save. Timesact removes that Customer Experience from the Timesact Cart Validation rule. To stop the rule for the whole store, open Settings → Checkout → Checkout rules in Shopify and turn off Timesact Cart Validation.

Show a pop-up for mixed carts

The mixed cart alert pop-up explains the mixed cart to shoppers in the store, before they reach checkout. It works on its own or together with Block checkout: the pop-up sets expectations, and Block checkout stops the order.

1. In the Customer Experience, go to Cart page → Pre-order tab → Mixed cart checkout.
2. Under Pop-up alert, turn on Enable mixed cart alert pop-up.
3. Under Alert content, edit Alert title, Alert message, Button text and Dismiss option text. The Preview updates as you type.
4. Under Button styling, pick the Button background color and Button text color.
5. Under Trigger settings, choose when the pop-up shows:
6. • Show on button click: after a shopper adds something to the cart and the cart now mixes pre-order and in-stock items.
   • Show on cart page: when a shopper opens the cart page with a mixed cart. This one is on by default.
6. Click Save.

The default mixed cart alert reads "Important Notice" with the message "Because your cart contains both in-stock products and out-of-stock products your order will be shipped when out-of-stock products are restocked." and an "Okay, Got it!" button. If you use Block checkout too, you can reword the alert to tell shoppers to check out pre-order items separately. When a shopper ticks the dismiss option, the pop-up stops showing in that shopper's browser.

Show a pop-up for pre-order items

The Cart alert pop-up sits on the same Cart page tab, above Mixed cart checkout. It shows for any cart with a pre-order item from this Customer Experience, mixed or not. A common use is having shoppers accept your pre-order terms.

1. Open Cart alert pop-up and turn on Enable cart alert pop-up.
2. Edit the Alert content. The default message is "By placing this order you acknowledge that you are informed about and agree to our shipping policy, our terms of service and our refund policy." with an "I agree" button.
3. Set Button styling and Trigger settings: Show on button click shows the pop-up when a shopper clicks the Pre-order button, and Show on cart page shows it on the cart page.
4. Click Save.

Questions merchants ask

Does Block checkout stop Shop Pay, Apple Pay and Google Pay?
Yes. Block checkout runs in Shopify's checkout through the Timesact Cart Validation rule, so it covers the normal checkout and every express checkout, including Shop Pay, Apple Pay and Google Pay.

I turned on Block checkout, but a mixed cart still reached checkout. What do I do?
In Shopify, go to Settings → Checkout → Checkout rules and turn on Timesact Cart Validation (use Add rule if it isn't listed). Then, in Timesact, open the Customer Experience → Cart page → Mixed cart checkout, turn off Block checkout when cart mixes pre-order and in-stock items and click Save, then turn it on again and click Save. Timesact sends your Block checkout settings to the rule when you save.

Can a shopper buy two pre-order products in one order?
Yes. Block checkout only stops carts that mix pre-order items with other items. A cart with only pre-order items checks out normally, also when the items come from different Customer Experiences, as long as each of them has Block checkout on.

Where do I change the message shoppers see when checkout is blocked?
In Timesact, in the Customer Experience under Cart page → Mixed cart checkout → Checkout error message. Edit the Message and click Save. Each Customer Experience has its own message.

Can the checkout error message show in different languages?
The checkout error message shows exactly as you type it in the app, in every language. On a store that sells in several languages, you can write the message in each of your languages, one after the other.

Do I need the mixed cart alert pop-up if Block checkout is on?
No, the two are independent. The mixed cart alert explains the situation while the shopper is still in your store, and Block checkout stops the order at checkout. Used together, shoppers already know why checkout asks them to split the cart.

Related articles

• [Plans, order usage and plan usage alerts](NEW: plans-and-plan-usage-alerts)
• Pre-order
• Shopify Order Tags
• Shipping Profiles and Locations
• Shopify Help Center: Checkout customization, Adding cart and checkout validation

Updated on: 11/11/2026