Why updating your Shopify theme wipes your customisations, and how to upgrade without losing them

If you run a Shopify store, you have probably seen the message. A new version of your theme is available. Click through and there is a second message: updating will not carry over your customisations.

So you leave it. Six months later there are three updates waiting, an app that does not work with your theme version, and a checkout feature you cannot turn on. This is one of the most common problems we get asked about, so here is what is going on and what to do about it.

Why updates do not carry customisations across

A Shopify theme is a folder of code files. When a theme developer releases a new version, they release a new folder. Shopify installs that new folder as a separate theme in your admin. It does not merge it with the version you are running.

Two kinds of changes live in your current theme:

• Settings changes made in the theme editor, such as colours, fonts, section order and content. Newer themes store these in a way that can often be carried across.
• Code changes made by a developer or an app. Custom sections, tweaks to product templates, tracking scripts, layout hacks. These live in the old folder and go nowhere on their own.

The more of the second kind you have, the bigger the gap between the update banner and reality.

Why it matters more than it used to

Shopify has moved a lot in the last few years. Online Store 2.0 brought sections on every page, better performance and metafields. Checkout has changed, and older customisations are being retired. Apps increasingly assume a modern theme.

If your store is on a theme from before those changes, you are gradually locked out of features, and page speed tends to drift downward as apps stack up scripts on an ageing base.

The safe way to upgrade

The process is the same whether you are moving to the next version of the same theme or to a completely new one.

1. Audit the current theme. List every code change, every app-injected snippet and every setting that matters. This is the step people skip, and it is the reason upgrades go wrong.
2. Install the new version as a separate, unpublished theme. Your store keeps trading on the old one.
3. Rebuild the customisations the modern way. Most old code hacks can now be done with built-in sections, blocks or metafields. Where custom code is still needed, it goes in as a clean section so the next update is easy.
4. Reinstall and reconfigure apps. Check every app on real product, collection and cart pages.
5. Test everything on a preview link. Desktop, mobile, every template, discounts, shipping, checkout.
6. Publish at a quiet time and keep the old theme as a backup. If anything is off, you can switch back in one click.

Done this way, a straightforward update is a small job. A move from a vintage theme to a modern one with lots of apps is a bigger one, because every app and customisation has to be checked on the new theme. Either way, the store never goes down.

What to do right now

Check the theme library in your admin. If the version number is well behind the latest, or the theme is marked as vintage, it is worth an audit. The audit alone will tell you how tangled things are and what the upgrade will involve.

We do these regularly, and we are happy to look at your store and tell you plainly whether it is a quick update or a proper migration.