What is actually changing

Shopify has been moving checkout away from legacy Liquid templates and script-based customisations for several years. checkout.liquid and Additional Scripts on the Thank You and Order Status pages were sunset on 28 August 2025. The remaining non-Plus deadline is 26 August 2026: Shopify will auto-upgrade stores still using the legacy pages, and legacy ScriptTags on those pages will stop working.

This matters more for measurement than for design. The visual checkout was already migrated for most stores through checkout extensibility. What tends to remain in the legacy surfaces is tracking: a Meta pixel purchase event, a Google Ads conversion snippet, an affiliate postback, sometimes a hand-rolled request to a warehouse endpoint.

Who this affects

You are affected if any of the following is true, regardless of how modern your storefront theme is.

• Your store is on Basic, Grow, or Advanced rather than Plus.

• You have anything at all in Settings, Checkout, Additional scripts.

• You installed a marketing tag by pasting code rather than through a Shopify app or the Web Pixels API.

• Your order status page contains custom tracking added before 2024.

What to check in your store

Additional scripts

Open Settings, then Checkout, and read the additional scripts field in full before you change anything. Copy it somewhere durable. Every distinct network call in that field is an event you will need to reproduce elsewhere, and the field is the only record of what was there once it is cleared.

How each pixel was installed

A Meta pixel installed through the official sales channel already uses Web Pixels and will survive. The same pixel ID pasted into additional scripts will not. Two stores can report the same pixel ID and have completely different exposure here, so check the installation path rather than the ID.

Order status page customisations

The order status page is the most common place for undocumented tracking to accumulate, because it is where post-purchase apps and agencies historically added their snippets. Treat anything you find there as in scope.

A migration checklist

Work through each legacy script and decide where its event belongs. Most fall into one of three destinations.

The important distinction is between scripts that observe and scripts that intervene. Observation moves to Web Pixels or webhooks. Intervention needs a checkout UI extension, which is a different and larger piece of work.

What happens if you miss the date

Nothing breaks loudly. Checkout continues to work and customers continue to buy. What changes is that some proportion of your purchase events stop reaching your ad platforms. A tracking interruption can change the conversion sample available to reporting and optimisation systems. The size and commercial effect require account-level validation.

The practical symptom is a step change in reported conversions that begins on a specific date and does not recover, usually alongside rising reported cost per acquisition while actual revenue holds steady. If you only look at platform dashboards, this reads as a performance problem rather than a data problem, which is why it often goes unfixed for a full quarter.

The check that settles it is simple. Count purchases in Shopify for a date range, count purchases reported by each ad platform for the same range, and compare the ratio before and after 26 August. A stable ratio means your migration held. A material ratio change around the migration date warrants investigation. It does not, by itself, identify the cause; attribution settings, consent, campaign mix and other implementation changes also need to be checked.