A Shopify theme update keeps the settings you've made in the theme editor but doesn't carry over changes you've made directly to the theme code. When you update a theme bought from the Theme Store, Shopify adds the new version to your theme library as a separate copy; colours, fonts, section settings and page templates are transferred to this copy. Code edits you've made in Liquid, CSS or JavaScript files, however, aren't transferred and need to be redone in the new version. Your live theme stays unchanged until you publish the new version.
In this article we explain what's kept and what's lost in a theme update, how to update safely and how to structure customisations so updates don't affect them.
What's kept and what's lost in a theme update?
Type of change | What happens in an update |
|---|---|
Colour, font and general theme settings in the theme editor | Kept |
Section and block settings, added sections, page templates | Kept |
Code added to the theme editor's "Custom CSS" field | Usually kept, as it's stored as a setting |
App blocks | Kept |
Code changes to Liquid files (sections, snippets, layout) | Not transferred |
Changes to CSS and JavaScript files in the assets folder | Not transferred |
New files added to the theme manually | Not transferred |
Code added to the theme by older apps | Not transferred |
Products, collections, pages, blog posts and customer data are independent of the theme and aren't affected by a theme update in any way.
How does a theme update work on Shopify?
When a new version of a theme bought from the Theme Store is released, an update notice appears next to the theme on the Online Store → Themes page.
When you start the update, Shopify adds the new version to your theme library as a separate theme and transfers your theme editor settings to this copy.
If your theme's code has been edited, Shopify warns you that these changes won't be carried over to the new version.
After previewing and checking the new version, you publish it. The old version stays in the library, so you can go back if needed.
This flow applies only to themes bought from the Theme Store. Updates for themes bought from other sites are done manually with files provided by the developer.
Steps to update safely
Duplicate your live theme. Take a backup by duplicating the theme on the Themes page.
List your code changes. If you don't know which files were changed and how, get this list from the theme's code history or your developer. If you use Shopify's GitHub integration, you can compare the changes directly.
Test the new version in preview. Check the homepage, product, collection, cart and checkout flows on mobile and desktop.
Reapply your code changes to the new version. Remember that some changes may no longer be needed in the new version, as the theme may now offer them built in.
Check your apps. Make sure app blocks are in place and check whether old app code is still needed.
Publish at a quiet time. Avoid changing themes right before campaign periods.
How do you protect customisations from updates?
Use the theme editor as much as possible. Changes made with settings, sections and blocks are kept in updates.
Add apps through app blocks. Prefer apps that support theme app extensions over older integrations embedded in the theme code.
Keep code changes in separate files. Creating a custom snippet or CSS file and calling it from the theme, rather than changing the theme's own files, makes reapplying changes after an update easier.
Document your changes. Record why and where each code change was made.
Consider newer themes like Horizon. Thanks to the theme blocks structure, many layout changes that used to need code can now be made in the theme editor and are kept in updates.
What if there are lots of code changes?
If a ready-made theme's code has been changed a lot, every update becomes a mini project. At that point there are two options: keep using the theme without updating and give up new features and bug fixes, or rebuild the customisations from scratch in a structure that updates don't affect.
That's why at Byte we build brand-specific designs not on top of ready-made themes but on a lightweight theme framework we've developed ourselves. Because the entire codebase is under our control, there's no risk of a third-party theme update breaking customisations. We explain this approach in detail in our article on paid and free themes.
Frequently asked questions
Does a Shopify theme update automatically?
You start updates for Theme Store themes yourself, and the new version doesn't affect your live store until you publish it. Your live theme doesn't change without your knowledge.
Will a theme update delete my products?
No. Products, collections, pages, blog posts and customer data are independent of the theme and aren't affected by updates.
What happens if I never update my theme?
Your store keeps working, but you miss out on new Shopify features, performance improvements and bug fixes. Themes that go without updates for a long time can develop compatibility issues over time.
Let's update your theme together
Updating a theme with code changes requires careful comparison and testing. To update your theme or move it to a structure that updates don't affect, get in touch through our Shopify technical support page.
