What Broke When Shopify Shipping Scripts Went Silent

You migrated your discount Scripts before June 30. You watched a Delivery Customization Function get deployed, tested it in the admin preview, and moved on. Your checkout still loads. No error page, no email, no red banner in your admin. So the migration worked, right?

Here is what my last four Plus-store audits since July 1 have found sitting under that surface.

What happened on July 1

Nothing visible.

That is the point. On July 1, Shopify's platform shipped a change that stopped a load-bearing checkout layer for every Plus store still running shopify shipping scripts. No admin banner. No email. Not even a "customizations affected" flag on the affected orders. Scripts stopped executing at some point around the June 30 cutover, and the checkout kept doing its job with the shipping conditions gone.

For a merchant whose PO Box Script had been quietly hiding UPS Next Day since 2022, July 1 looked exactly like June 30. The next customer to enter a PO Box address saw every express carrier the store offered, picked one, and paid for a label the carrier would not honor. UPS attempted delivery, could not deliver to a PO Box, held the package, and eventually returned it. The merchant paid the outbound label, ate the return, refunded the shipping, and now has a support ticket to close.

That whole sequence happened without any signal from Shopify that a Script had stopped executing.

Why the discovery has been so slow

The first thing my audits keep surfacing is which Scripts the team actually remembered they had. Almost every Plus team I looked at knew about their discount Scripts and migrated those first, because discount failures are visible in dollar terms. Broken BOGO shows up in the average order value within a week. That kind of failure is loud.

Shopify shipping scripts are the opposite. They usually block or hide an option that most customers do not need. A rural-postcode surcharge Script fires for maybe two percent of your traffic. A PO Box hiding Script fires only for customers who type a PO Box in the address field. A wholesale rate gate fires only for tagged customers checking out. The Script can be dead for weeks before a triggering customer places an order and something visible goes wrong.

The fudge.ai newsletter noted in mid-July that verified "my store broke on July 1" reports were scarce in public forums. That is not evidence the migrations landed cleanly. It is evidence that the affected cohorts on each store are small and slow to trip the wire.

I have been telling clients that the correct expectation for post-shutdown discovery is measured in months, not days. The stores that catch it fastest are the ones running post-July 1 test orders with the exact address, tag, and cart shapes their Scripts checked for. The stores that catch it slowest are the ones where nobody on the current team even knows what conditions the Scripts were checking. In one recent audit, the developer who wrote the Script left the company in 2023. Nobody I talked to could tell me what the address regex was looking for. We read the Ruby code together, out loud, for about forty minutes.

What I changed in my audit checklist

Three things.

First, the Script Editor app itself is now a diagnostic flag rather than a green tick. If Script Editor still appears in a Plus store's app list, that store had active shopify shipping scripts at some point before April 15. The Scripts are dead now, but the Ruby code is still readable inside the app. I open every Script and write out in plain English what condition it checked and what it changed. This is the single most valuable step for teams whose original developer is gone. If you want a second pair of eyes on that read-out, the first 15 minutes with a help1 expert are free and it is usually enough to name what is missing.

Second, I test the Delivery Customization Function replacement with the "change your address" flow. This is the DCF bug that Shopify Staff (Nick Wesselman) confirmed back in December 2023 and never publicly announced a fix for: when a DCF hides all rates in response to a PO Box, and the customer then edits the address to remove the PO Box text, the function does not re-run. Rates stay hidden until the customer manually refreshes the checkout page. Most customers do not refresh; they abandon.

If your PO Box replacement rule hides every rate, you now own that bug on top of the original problem. The workaround I use is to leave at least one rate visible, even if it is a $0 "Please contact us" placeholder that no customer would actually pick. That keeps the function's re-evaluation trigger firing on the next address edit. I have not confirmed whether Shopify quietly fixed this in 2026 for the newer checkout renderer, so treat the workaround as belt-and-braces rather than an assumption about the bug being live.

Third, I ask a question I did not ask before: do you sell on subscription. Delivery Customization Functions do not run on subscription renewal orders. Renewals are generated through the draft order API, and DCF is checkout-only. If a store used shopify shipping scripts to gate carrier options on subscription renewals, there is no direct replacement. You end up negotiating with the subscription app vendor about whether their software can enforce a delivery method at the app level, and no major subscription app I have looked at has a documented answer for this.

What I would catch earlier next time

I told a client on June 28 that the two-week margin from their discount-script migration to the shutdown was fine, because the shipping Script they had was "simple." I was wrong. Their PO Box logic combined an address regex with a specific line-item property check, and the app they installed (HideShip) covers the address side but not the line-item side. They found the gap on July 9 through a customer complaint about USPS Ground being unavailable on an order that should have been eligible. We rebuilt the rule as a custom Function later that week, but the two weeks in between produced twelve returned packages.

Two things I would do differently. I would treat "simple" as a red flag rather than a green one; simple Scripts are more likely to combine conditions in ways no-code apps do not cover, and the merchant just did not know they were combined. I would also insist on a live-checkout test on July 1 itself, not a preview. Admin preview does not reproduce every checkout path, and the whole discovery problem is that failures only show up in real carts. If your Plus store had shopify shipping scripts and you have not run a live checkout on the affected paths since July 1, that is the audit you owe yourself this week. If you want the diagnostic in one pass, the free help1 app surfaces Script Editor as a shipping-health flag on Plus stores.

Shipping infrastructure on Shopify is one of those things that stops making noise the moment nobody is looking, and then keeps not making noise for weeks.