Mixed carts: preorder and in-stock items in one order (Essential Preorder app)
This article explains what happens when a customer has both a preorder item and an in-stock item in the same cart, how the campaign’s fulfilment status decides that, and how to stop customers mixing them at all. It is for shop owners who have had customers ask about split deliveries, or who want preorder and regular items kept in separate orders.
If you are setting up a preorder campaign for the first time, read How Preorder Campaigns Work first.
Where the setting is
Open the preorder campaign, Content tab, section Shipping & mixed carts. It has two parts that work together:
- Fulfilment status: Unfulfilled, Scheduled or On hold. This is the setting explained in Fulfil preorders: on hold, scheduled, tags and releasing orders.
- Mixed cart handling (“What happens when a cart has both preorder and in-stock items”): two options and a checkbox.
The fulfilment status decides the mixed cart option
You do not pick the mixed cart option freely. The app selects it from your Fulfilment status, and greys out the other one with a Coming soon badge.
| Fulfilment status | Mixed cart option the app selects | What happens after checkout |
|---|---|---|
| Unfulfilled | One fulfilment for preorders & regular items (“One order, one shipping charge. All items fulfillable now.”) | One order, one fulfilment. Everything can be fulfilled straight away, including the preorder line. |
| Scheduled or On hold | Split fulfilment for preorders (“Preorder and in stock items are split into 2 fulfilments after checkout”) | One order, two fulfilments. The in-stock items sit in a fulfilment you can ship now. The preorder items sit in a separate fulfilment that is held (On hold) or scheduled (Scheduled) until you release it or the date arrives. |
In both cases it is one Shopify order and one shipping charge, set by your Shopify shipping rates at checkout. The split only changes how the order looks in your Shopify admin and what you can ship when.
The greyed-out option is not available for that fulfilment status. If you want the other behaviour, change the Fulfilment status.
These two options are available on every plan. Only the checkbox below needs the Starter plan.
Blocking mixed carts entirely
If you do not want customers combining preorder and in-stock items in one order at all, tick Don’t allow mixed carts (“Customers get an error message when adding to cart”). The app stops the add to cart and shows your message. If something still gets through, checkout is blocked with the same message.
- Write your own wording in Error message. The default is Preorders need to be purchased separately from regular items. Remove one of the items to proceed to checkout.
- The message is translatable, so it can show in each of your store’s languages. The translation field is called Mixed cart error message.
- Free gift with purchase lines added by other apps are ignored by this rule. They do not block the cart.
- This checkbox needs the Starter plan or higher. On Free and Lite it is read only and shows Upgrade to Starter to control mixed carts.
What mixed cart handling does not do
- It does not split one order into two orders. The customer places and pays for a single order.
- It does not charge shipping twice. One shipping charge at checkout, whether the order ends up with one fulfilment or two.
- It cannot create a separate order for the preorder items only. If you need that, use Don’t allow mixed carts so the customer places two orders.
- It does not split a single product line into part in stock, part preorder. If a customer wants 4 units and you have 2 in stock, all 4 are treated the same way.
What Shopify itself does with shipping rates, shipping profiles, multiple fulfilment locations or Shopify Markets is controlled by your Shopify settings, not by this app. If shipments split or combine in a way you do not expect, check your Shopify shipping profile and fulfilment location setup first.
Finding mixed cart orders in your admin
Every order that contains at least one preorder item is tagged under Order tags (“For orders containing preorder items”), so you can filter these orders in Shopify admin. Customers who place preorders are tagged too, under Customer tags. Both tags are set on the campaign’s Content tab.
The app also adds a Preorder note (“Visible in cart, checkout, transactional emails”) next to each preorder line, so you and the customer can see which items in a mixed order are on preorder. Edit the wording in Note text, referenced by Note key.
Still stuck?
If your fulfilment app or 3PL rejects an order with two fulfilments, or an order does not match the setting you chose, contact support with the order number, the campaign’s Fulfilment status, and the name of any fulfilment or shipping app you use.