On Wednesday 26 August 2026, Shopify replaced the legacy Thank You and Order Status pages for every store that is not on Shopify Plus. Most of the coverage was about upsell widgets and surveys disappearing. The part that costs money is quieter: the Additional Scripts box under Settings → Checkout was removed, not migrated. Whatever was pasted into it — conversion pixels, affiliate tags, a GTM container, a survey trigger — stopped running that morning.
Why nobody noticed
Nothing tells you. Orders keep arriving, because orders are recorded on Shopify’s servers. Revenue looks normal. No error appears anywhere in the admin, and none appears in Meta or Google either, because from their side nothing broke — they simply heard about fewer purchases.
The only thing that disappeared is the browser event: the moment where the customer’s browser told your ad platform “a purchase just happened”. Meta, Google and TikTok all optimise against the conversions they were told about. Tell them about fewer, and they bid as if your store converts worse than it does. A week later it looks like your ads mysteriously got expensive. We have watched people rewrite creatives and raise budgets when the actual problem was measurement.
The 5-minute check
- Place a real test order. Cheapest product, real card, refund it afterwards — a preview is not enough, because the failure is on the live thank-you page. While you do it, watch the ad side: Meta Events Manager → Test Events, GA4 Realtime, TikTok Events Manager. If the purchase does not arrive within a minute, you have your answer.
- Compare a few recent days. Orders in your Shopify admin against the purchases each platform reports, for the same days, in your store’s timezone. If the two numbers tracked each other before the 26th and drift apart after it, the migration missed something. Do not compare a single day — attribution windows make one day noisy — compare a week.
- Look at Settings → Customer events. Pixels named “Meta pixel (migrated)” or “Google Analytics tag (migrated)” came from an earlier, separate auto-migration in February 2025 and most likely survived. Now notice what is not there: TikTok, Pinterest, Snapchat, Klaviyo, a GTM container, affiliate tags. None of those were ever migrated out of Additional Scripts. Nothing rescued them.
If something is broken
Install the official Customer Events integration for each platform — Meta, Google and TikTok all have one now, under Settings → Customer events → Add pixel. That is the supported path and it gets first-party data the old snippets never had.
What not to do: paste your old snippet into a custom pixel. A custom pixel is not the Additional Scripts box with a new name. It runs in a sandboxed frame beside the page, with no access to the storefront DOM, to window.Shopify, or to your dataLayer. Legacy code that reads Shopify.checkout.order_id throws inside that sandbox — and the page carries on as if nothing happened, so your test order goes through and you conclude the migration worked. It did not.
And anything you genuinely cannot afford to miss — an affiliate payout, a conversion that drives a budget — belongs on a server-side order webhook, not in a browser that can be closed a second early.
Doing the check every day
Step two above is the whole idea behind Conversion Monitor, the free Shopify app we build: it counts your real orders against the purchase events your tracking actually reported, per day, in your store’s timezone, and shows the difference in dollars of ad spend being optimised on incomplete data. It fixes nothing and recommends nothing; it is the number, every day, and an email the day it changes. But the manual check above works without it. Do the check.