Shopify's legacy checkout customisations are gone. Check what stopped working

Shopify's move to Checkout Extensibility is now complete across all plans. The old ways of customising checkout and the post-purchase pages are retired: checkout.liquid, Additional Scripts, and script tags on the Thank you and Order status pages. In their place are checkout UI extensions, web pixels and Shopify Functions.

Most stores migrated on time. Some didn't, and the problem with this change is that nothing visibly breaks. The checkout still works and orders still arrive. What disappears is everything that relied on those scripts.

What tends to fail without anyone noticing

• Conversion tracking pasted into Additional Scripts for ad platforms and affiliate networks
• Post-purchase surveys and "how did you hear about us" widgets
• Upsell or referral offers shown on the Thank you page
• Custom fulfilment or CRM integrations triggered from Order status page scripts

How to check your store

Compare your ad platform conversion counts against Shopify order counts week by week, going back a few months. A sudden drop with no change in sales usually means tracking was lost when the legacy scripts were switched off. Then place a test order and go through the Thank you and Order status pages, checking that everything you expect to see is there.

The fix

Tracking moves to web pixels, configured through the Customer events section of the admin. Visible customisations move to checkout UI extensions, either from the App Store or as custom app extensions. Most rebuilds are small and bounded once you know exactly what was lost.