Updated September 11, 2026. Dates are as published in Shopify's developer changelog entry of August 24, 2026. Third-party products are named to identify them only.
On October 1, 2026, Shopify's ScriptTag API stops accepting create and update calls on every API version, and on March 1, 2027 Shopify stops injecting existing script tags into storefronts. Any app feature that still runs on the storefront through a script tag stops working on that second date, with no change to the theme and no error shown to the shopper. The dates come from Shopify's developer changelog entry of August 24, 2026.
This article explains what a script tag is, why the change matters more to merchants than to developers, how to tell from the outside whether a store is affected, and what to ask each app vendor. A free outside check of any Shopify storefront is at index.statusbird.io/october-1.
What is a Shopify script tag?
For most of Shopify's history, an app that needed to run code on a storefront could register a script through the ScriptTag API. Shopify then injected a <script> element into every page of the store, loading the app's JavaScript from the app's own server. Reviews widgets, pop-ups, upsells, analytics, chat bubbles, currency switchers and fraud tools all used it, because it worked on any theme without the merchant touching a line of code.
The replacement is the theme app extension. An app embed block or an app block is added through the theme editor, rendered by Shopify from the app's extension bundle, and can be switched on and off per theme. Shopify has been steering developers toward extensions for years; the August 2026 changelog sets the end date for the old mechanism.
What exactly changes on each date?
- October 1, 2026. The
scriptTagCreateandscriptTagUpdatecalls return errors on every API version. An app can no longer register a new script tag or change an existing one. Existing tags keep loading. A merchant who installs an app that still relies on script tags on or after this date gets an app that cannot set itself up. - March 1, 2027. Shopify stops injecting script tags into storefronts. Every remaining legacy tag stops loading. Whatever the app did through that script stops with it.
Nothing happens to the theme, the app stays installed, and the app's admin pages keep working. The failure is on the storefront only, which is exactly where a merchant does not look every day.
Why is this a merchant problem rather than a developer problem?
The changelog is published on shopify.dev for app developers. It is a well-run app vendor's job to migrate, remove old tags, and tell merchants. Many will. But a merchant has no direct view of which mechanism each installed app uses, so the merchant's exposure depends on the diligence of every vendor on the store, including the ones that are no longer actively maintained. The apps most likely to miss the deadline are the ones least likely to send a notice.
An agency that built stores for clients carries the same exposure across its whole roster, and a client who loses a feature in March will ask the agency first.
How can I tell from the outside whether a store still uses script tags?
A script tag injected by the ScriptTag API has a recognisable shape in the page source. Shopify renders it in the document head as <script type="text/javascript" async="" src="https://app.example/script.js?shop=yourstore.myshopify.com">: the async="" attribute with an empty value, a shop= parameter carrying the store's myshopify domain, and a host that is not Shopify's own CDN. A script loaded by a theme app extension looks different: it sits inside a block that Shopify marks with an app block comment or a shopify-block wrapper, and is served from Shopify's CDN.
The free check at index.statusbird.io/october-1 fetches a store's homepage once, applies that rule, and names the app behind each legacy tag where the script host is known. It also tells the two cases apart: a store that carries only a legacy tag for an app is at risk, and a store that carries both the app's extension and an old tag is "cleanup only", because the extension keeps working after March 1. The full method is published on the index's methodology page.
What should a merchant do before October 1?
- List the apps installed on the store. The list is in the Shopify admin under Apps.
- Run the outside check on the storefront. It shows which apps, if any, still load on the homepage through a legacy tag.
- Ask each at-risk vendor one question: what is the date of your theme app extension release, and does the update remove the old script tag? A vendor with a date and a published notice is fine. A vendor with neither is a replacement decision.
- Replace before March 1, 2027. After October 1 a replacement app that still uses script tags cannot install itself, so the window for swapping apps that have not migrated is effectively the month of September.
- Check product, collection, cart and search pages too. Some apps inject only on those templates, so a clean homepage is necessary but not sufficient.
What should an agency do?
Check every client storefront in the portfolio, keep a dated record of the result for each, and send clients with an at-risk app the vendor question above. A dated record matters because storefronts change: a store that was clean in September can add an app in November. The October 1 Index issues one-page portfolio records and a badge for agencies whose client stores checked clean, and lists agencies who ask to be listed for merchants that need a migration done.
Does this affect checkout, tracking pixels or Shopify Plus?
The ScriptTag deprecation applies to storefront pages. Tracking that runs through Shopify's web pixels is a separate mechanism and is not affected by this change. Checkout customisation on Shopify Plus has its own migration path and its own dates, which are outside the scope of this article. If an app documents that it uses a theme app extension or a web pixel, it is on the supported side of this change.
Frequently asked questions
Will my store break on October 1, 2026?
Not on that date. On October 1 apps can no longer create or update script tags; existing tags keep loading until March 1, 2027, when Shopify stops injecting them and the affected app features stop working on the storefront.
How do I know which of my apps use script tags?
Run an outside check of your storefront, which identifies legacy script tags by their shape in the page source and names the app behind each one where the host is known. Then ask any vendor named for its migration date.
What is the difference between "at risk" and "cleanup only"?
At risk means the app loads on the store only through a legacy script tag, so its storefront feature stops on March 1, 2027. Cleanup only means the app's theme app extension is already present and an old tag remains; nothing breaks, and the vendor should remove the leftover tag.
Is a theme app extension the only replacement?
For storefront features, the theme app extension is Shopify's supported replacement. For analytics and marketing tracking, Shopify's web pixels are the supported mechanism. Both are unaffected by the ScriptTag deprecation.
Where do the dates come from?
From Shopify's developer changelog entry of August 24, 2026, which states that ScriptTag create and update calls return errors on October 1, 2026 and that injection into storefronts stops on March 1, 2027.
Check any Shopify storefront free at index.statusbird.io/october-1. The October 1 Index is an independent research service of StatusBird LLC, and every named vendor has a free right of reply, a migration notice link and a verified migrated status available on the index.
StatusBird LLC is not affiliated with, endorsed by or sponsored by Shopify Inc. Shopify, Shopify Plus and Shopify App Store are trademarks of Shopify Inc. App names are used to identify the products only. The October 1 Index is an independent research service of StatusBird LLC and is not a Shopify app.