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17 September 2026
1 October 2026: nobody will be able to create or edit a script tag
From that date, the calls that create or update a script tag return an error. Script tags already in place keep working until March 2027. This is the date that closes the door on quick fixes, not the one that breaks anything.
What exactly changes
Shopify states that the scriptTagCreate and scriptTagUpdate operations will return an error from 1 October 2026. In practice, an app can no longer place a new script on your store this way, nor fix the one it placed earlier.
Script tags already in place keep loading. Nothing disappears that day. A door closes, no switch is flipped.
Who will notice, and how
Stores installing a new measurement app after that date. If the app has not moved to theme app embed blocks or web pixels, the install will look successful and nothing will load. That is the kind of failure you find three weeks later, wondering why the numbers are flat.
Stores where an existing app needs to edit its script, say to change an ad account ID or fix a bug. The update will fail, and depending on how the app handles the error, you may never hear about it.
Agencies running a portfolio of stores. A fix applied to thirty stores at once, through script tags, will not go through.
What to have done before
List what still loads through a script tag on your store. It is rarely a single app: an ad pixel, a reviews tool, a consent banner and a loyalty script can all sit there without anyone remembering.
For each app involved, ask its publisher whether the migration is done and when it was deployed on your store. An app updated on the app store does not mean a migrated store.
Republish what needs it: measurement and conversions as web pixels declared under Customer events, anything shown on screen as app embed blocks or checkout extensions.
The trap in this date
Because nothing breaks on 1 October, it is tempting to treat it as a developer deadline. But the stretch between that date and 1 March 2027 is exactly when you will need to make corrections, since that is when stores discover the damage done over the summer. And it is the stretch where the simplest repair tool is no longer available.
A store that waits for March will have to redo everything at once, in peak season, with no way to patch in the meantime.
Sources
Find out what is already broken on your store
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