Short answer: a pre-order lets a product be bought while it has no stock, and that needs the variant to allow selling at zero. If the setting is left on after the campaign ends, the product stays sellable without limit and without the pre-order terms. Restore it per variant when the campaign ends, and turn campaigns off before you uninstall a pre-order app.
What "Continue selling when out of stock" does
In the Shopify admin the option sits in the Inventory section of a product or variant. It can only be selected when the Inventory tracked setting is on. Without it, customers cannot buy an item once its inventory is at zero or below; with it, they can (Shopify Help: selling out of stock products). Shopify names pre-orders as one reason to use it. The setting does not apply to orders placed in Shopify POS.
Why that setting is risky after a pre-order
While a pre-order campaign runs, selling past zero is the point. When the campaign ends, Shopify does not know that it is over, so the setting stays on until you or an app switches it off. The variant keeps accepting orders, with no limit, and those orders are normal purchases rather than pre-orders. For a product you cannot restock quickly, that is how a store can end up owing more units than it can ship.
How to check your store
- Open a product that had a pre-order campaign.
- Open each variant and look at the Inventory section.
- If "Continue selling when out of stock" is on for a product that is meant to sell out normally, switch it off and check the quantity.
Check every variant, not only the first one. If you have more than one active location, inventory is assigned per location, and Shopify's section on overselling with multiple locations explains how that changes which items show as out of stock.
The safe way to handle it
- Before the campaign, note each variant's current setting.
- When the campaign ends, put every variant back to its previous setting.
- If you run an app that changes the setting for you, find out whether it restores the original value, and whether it does so per variant.
Before you uninstall a pre-order app
Shopify says that if you uninstall a pre-order app, the pre-order data you created in it is deleted after 48 hours (Shopify Help: Pre-orders). Shopify's note is about pre-order data and does not mention the "Continue selling" option, which is saved on each variant, so check it separately. The simplest rule, for any pre-order app: turn your campaigns off first, then uninstall.
How Dropsoon handles it
Dropsoon switches overselling on only while a campaign runs, and restores each variant's previous setting when the campaign ends or you turn it off. If you set a pre-order quantity limit, Dropsoon saves each location's stock first and puts it back when the campaign ends. The same rule applies to us: uninstalling alone does not restore your settings, so turn campaigns off in the app before you uninstall. If you have already uninstalled, reinstall Dropsoon and turn the campaign off within 48 hours of uninstalling to get the original settings back.
Last checked: 14 October 2026. Sources: Shopify Help: selling out of stock products, Shopify Help: Pre-orders.