A theme update and a theme change sound alike, and owners often fear them for the same reason: something that worked yesterday might not work tomorrow. They're different jobs. An update keeps your theme and moves it to a newer version. A change swaps the whole theme for another one.
What breaks in each comes from the same place more often than not, which is custom code that nobody wrote down. This article explains what each one keeps and what tends to break, then how to do either without surprises.
In short
- A theme update is added as a draft copy of your theme. Theme editor settings come across, and code edits come across only if they don't clash with the new version.
- A theme change keeps your products and pages, but your layout, wording, code edits and templates are set up again in the new theme.
- In both, the usual cause of breakage is custom code nobody documented, from a past developer or an old app.
- Neither touches your live store until you publish. Duplicate first, test the draft, then publish.
How to use this article
Give it fifteen minutes. If you have a theme update waiting in your admin, keep that page open.
Start with the comparison. It shows what each job keeps and what it doesn't. Then go through the six things that break, each with the same four parts: what breaks, why, whether it's an update or a change problem, and how to prevent it.
Finish with the decision rule. It tells you whether your theme needs an update or a change.
Update or change, in plain words
A theme update is a newer version of the theme you already use, released by its developer. When one is available, Shopify shows it in your admin. Choosing to add it puts an "Updated copy of" your theme in your draft themes, which, in Shopify's words, "doesn't impact your current theme or any other themes". You review it, then publish it when you're ready.
A theme change means publishing a different theme altogether: moving from Debut to Dawn, or from Dawn to a paid theme. The new theme starts from its own defaults.
Here is what each keeps, from Shopify's own help pages on updating and changing themes:
| Theme update | Theme change | |
|---|---|---|
| Products, collections, pages, menus, blog posts | Kept | Kept |
| Settings, layout and content set in the theme editor | Copied across | Set up again |
| Code edits | Copied, unless they clash with the new version | Redone, or dropped |
| Templates you created | Usually kept, check them | Rebuilt |
| Apps switched on in the theme | Check each one | Switched on again |
| The live store while you work | Unchanged until you publish | Unchanged until you publish |
The two rows that decide how hard the job is are code edits and templates. Everything else either comes across or is quick to redo.
What about automatic updates? Separately from the updates you choose, Shopify applies automatic updates to fix bugs or security issues. It says these "don't modify the look and feel of your theme or make any changes to your content or settings". They aren't the updates this article is about. The ones that can break things are the version updates you add and publish yourself.
Six things that break, and why
1. Code edits that clash with the new version
What breaks. A feature someone added in code stops working, or disappears, after an update.
Why. An update replaces the theme's files with the developer's new versions. Shopify carries your code edits across when it can, and when it can't, it tells you with a message: "Theme added: code edits could not be included". Those changes then have to be copied into the new version by hand.
Update or change? Both. In a change, none of the code edits come across, because the new theme is built differently.
How to prevent it. Shopify's advice is to "always save a copy of any customized code before updating your theme". Better still, keep a written list of every code change, so nobody has to find them again.
2. Templates you added since the last update
What breaks. Pages or products that used a special template fall back to the default look.
Why. On Shopify Community, an owner on Horizon reported that their last two updates had caused newer page templates "to revert to using a default page template". A reply explained the likely reason: "A Horizon update replaces the theme's files with the new version's files," and a template added since the last update may not be part of what gets merged.
Update or change? Both. In a change, every template has to be rebuilt in the new theme anyway.
How to prevent it. Before publishing an update, open each special template in the draft and check the products and pages assigned to it.
3. Code that old apps wrote into the theme
What breaks. A widget from an app you still use goes missing, or one from an app you removed years ago comes back to life in a strange way.
Why. Some older apps installed themselves by writing code straight into your theme files. To an update, that code is just another code edit, and it can clash like any other. In a theme change, it doesn't come across at all. Shopify notes that some app code "isn't automatically removed when you uninstall the app", so a theme can carry code from apps nobody remembers.
Update or change? Both.
How to prevent it. List the apps that show something on your store and check each one on the draft. Our article on the apps a small store needs covers how to find leftover code.
4. App switches that need turning on again
What breaks. An app's widget or pop-up isn't there on the new theme.
Why. App blocks and app embeds are switched on per theme. Shopify says that after you change your published theme, you'll need to reactivate your apps in the new one.
Update or change? Mostly a change. After an update, check each app on the draft anyway, because Shopify asks you to make sure your apps are compatible with the new version.
How to prevent it. Switch every app on in the draft and test it before publishing.
5. Custom styling that targets old parts of the theme
What breaks. Colours, spacing or fonts that someone set with custom CSS stop applying, or apply to the wrong thing.
Why. Custom styling points at named parts of the theme. If the new version renames or removes those parts, the styling points at nothing. Shopify's update page tells you to check that your custom CSS selectors still exist in the new version.
Update or change? Both, and in a change almost always.
How to prevent it. Look at the draft on a phone and a computer, page by page, against screenshots of the live store.
6. Things you only notice when someone buys
What breaks. The cart, a discount field or the path to checkout behaves differently, and nobody notices until orders drop.
Why. The editor preview shows pages. It doesn't place orders. An owner on Shopify Community wrote after a theme switch that "The cart isn't working since we switched", and put the cost at over $5,000 a day.
Update or change? Both.
How to prevent it. Place a test order on the draft before publishing, and watch orders for the first few days after.
The six at a glance
| # | What breaks | Update | Change | Prevent it by |
|---|---|---|---|---|
| 1 | Code edits | When they clash | Always redone | A saved copy and a written list |
| 2 | Templates added since the last update | Can reset | Always rebuilt | Checking each template on the draft |
| 3 | Code old apps wrote into the theme | Can clash | Doesn't come across | Checking every app on the draft |
| 4 | App switches | Check each | Turned on again | Switching on and testing before publishing |
| 5 | Custom styling | Can stop applying | Usually stops | Comparing the draft with screenshots |
| 6 | Cart and checkout path | Possible | Possible | A test order before publishing |
Custom code nobody remembers
Every problem above is easier when someone knows what was changed in the theme. In many stores that have been running for a few years, nobody does.
It builds up quietly. A developer adds a delivery message in year one. An app writes its code into the theme in year two and gets uninstalled in year three, leaving the code behind. A freelancer fixes a layout bug with some CSS. None of it is written down, and the people who made the changes have moved on. An owner switching themes on Reddit, unable to work out what the original builder had changed, summed it up: "I am missing much of the custom work."
The result is a theme that works but can't be touched safely. Updates get skipped because they might break something. A theme change looks like a leap into the unknown. Owners in that position are often told the safest move is to start from scratch, which is rarely necessary once someone lists what's there.
How to find it. When Shopify can't carry code edits into an update, it tells you, and its update page suggests using a comparison app from the Shopify App Store to find the differences. A developer can also compare your theme's files with a clean copy of the same version and list every change. That list is the document to have before any theme work. For each change it should say what it does, which file it's in, who made it and when, and whether it's still needed. A few lines per change is enough, and the next person to touch the theme starts from facts.
Update or change?
- Is an update waiting, and does your theme have no code edits? Add it as a draft, check it, publish. This is the routine case.
- Is an update waiting, and your theme has code edits? Add it as a draft, read the message about code edits, and test the six points above before publishing.
- Did the last update leave code edits behind, or do you keep paying to put the same changes back? That theme has outgrown its edits. List them, then decide whether to rebuild them or move to a theme that does those things without code.
- Is your theme a vintage one? There are no updates to take. Shopify says such a theme "has been sunset and is no longer updated by Shopify", and its advice on the same page is to "consider upgrading to a newer theme, or seeking the assistance of a Shopify Partner". The decision is when to change, and our article on being stuck on an old theme sets out how.
When an update won't help
An update fixes bugs and adds what the developer has built since your version. It doesn't change what kind of theme you have. Updating a theme that can't put sections on product pages won't add them, and updating won't speed up a store that's slow because of its apps and images.
Updates also only reach themes installed from the Theme Store. Shopify says themes bought elsewhere don't get updates through your admin, so their updates depend on whoever sold them.
And an update doesn't answer the bigger question of whether the theme still fits. Shopify's own update page suggests using the moment to consider whether your current theme still meets your needs. If the main reason you're updating is to stop paying for the same fixes again and again, answer that question first. Sometimes a theme change is the better spend, because it leaves you with a theme you can edit yourself.
A safe update, step by step
- Duplicate the live theme. A backup that costs nothing.
- Save a copy of any custom code, or better, write the list of changes if you don't have one.
- Add the update to your draft themes. The live store doesn't change.
- Read the message. If it says code edits couldn't be included, list what's missing before going on.
- Check the draft against the six points. Templates, apps, styling, and every page type, on a phone and a computer.
- Place a test order on the draft.
- Publish at a quiet hour, keep the old version in your library, and watch orders for a few days.
Do it yourself, or hand it to us?
What it takes on your own. A clean update is a draft, a check and a test order. The rest is where the time goes: finding code edits that couldn't be included, comparing files with a clean copy of the theme, checking every template, app and page type on a phone and a computer, and copying changes across by hand. Without a list of what was changed, every update is detective work.
What we do. We list every code change in your theme, what it does and whether it's still needed, then take the update or move you to a theme that does those things without code, tested with a real order before anything goes live. You keep selling meanwhile, and the work takes us days. That's our Store Design & Theme Development work.
Questions store owners ask
Will updating my Shopify theme delete my customisations?
Theme editor customisations are copied to the updated version. Code edits are copied too, unless they clash with the new version, in which case Shopify tells you and they have to be copied across by hand.
What does "code edits could not be included" mean?
It means some of the code changes in your current theme clashed with the new version, so Shopify left them out of the updated copy. Your live theme is unchanged. Those edits need to be found and added to the new version before you publish it.
Do I have to update my Shopify theme?
No. Updates are added as drafts and only go live when you publish them. Shopify does apply automatic updates for bugs and security, which it says don't change your theme's look, content or settings.
Are Shopify theme updates free?
Yes, for themes installed from the Theme Store, free or paid. Themes bought outside the Theme Store get no updates through your admin.
Is it safer to update my theme or change it?
An update keeps much more of your work, so it's usually the smaller job. A change makes sense when the theme itself is the limit, for example a vintage theme that gets no updates.
Why did my pages change after a Horizon update?
Owners have reported templates added since the last update falling back to the default after updating. Check each special template on the draft before publishing, and keep a duplicate of the live theme.
Afraid to press update? Get a free Store Audit
Send us your store URL and we'll send your Store Audit the same day: your theme and its version, what it can't do, the old code still in your theme, and the app scripts that stop on 1 March. It's free.
