PrestaShop theme update lost my changes: how to get them back and protect them next time
When a PrestaShop theme update lost your changes, the author's new files overwrote your fixes. You can recover them from a copy of the files from before the update: from your host, from the developer or from the old theme package. Then move them to a child theme. An update of the parent theme does not touch it, so the changes will not disappear again.
Author: The TellMyShop team. A guide for PrestaShop store owners: the cause, the manual fix and the same work in a chat conversation.
Last updated: · 6 min read
What does it usually look like after an update?
It starts with a small thing someone notices a few days later. Friday, 22:05, a customer writes that she cannot see the free delivery note on the product page. A developer added that text a year ago, directly in a theme file. On Wednesday the theme got an update from its author, with bug fixes and a new cart design.
The update did what it was supposed to do. It replaced the theme files with new versions. With them came back the old button colours, and the note in the footer and the delivery text disappeared. Nobody kept a list of those changes, because “they're in the store anyway”.
Why does an update overwrite changes in the theme?
Because the theme files belong to its author, and an update swaps them for new ones. That applies to bought themes and to the Classic theme. The PrestaShop update assistant has a separate option for updating the default theme, described in the update instructions. When it is on, Classic goes back to the version from the new release.
PrestaShop's answer to this problem is the child theme. It is a separate theme that inherits everything from the parent and overrides only the files you change in it. The mechanism is explained in the child theme documentation, and Biegun.Studio has a guide with examples (in Polish).
Where can you get the version from before the update?
Check, one by one, the places where a copy may have survived.
| Source | What it contains | What to watch out for |
|---|---|---|
| Your host's backup | files from the day of the backup | restore single files to a separate folder, not the whole store |
| The developer who made the changes | their versions of the files | they may have a list of changes worth asking for |
| The package of the old theme version | the author's files without your changes | lets you compare and find the differences |
| File copies from TellMyShop | files changed by the chat | only changes made by the chat |
| A web archive in the browser | the look, not the code | helps recreate texts and layout |
Do not restore the whole store from a backup to recover a few lines in the theme. You would lose orders and catalogue changes from the last few days. Restore the theme files to a separate folder and compare them with the current ones.
How do you move changes to a child theme?
The order matters, because you turn the child theme on only at the end.
- List the changes that disappeared: the file, the place and what was there.
- Create a child theme of your current theme.
- Copy only the templates you are changing into the child theme and make your fixes in them.
- Add your own styles to the child theme's custom.css file.
- Make changes to the look of modules in copies of their templates inside the child theme.
- Turn on the child theme in Design > Theme & Logo.
- Clear the cache and check the home page, a product page, the cart and checkout. Also check the order of blocks in Design > Positions.
- Keep the list of changes in one place, together with the file names.
If you are changing colours, read how to change the button colour with custom.css. icomSEO also writes more broadly about editing a template (in Polish).
What does not disappear in a theme update?
Everything stored in the database rather than in theme files. Text translations, module settings, the order of blocks on the home page, the content of information pages and product descriptions all stay. That is why some changes are better made there than in the template. For example, you can often change the PrestaShop line in the footer in translations, without editing a file.
How do you avoid losing changes in the next update?
Before every update of the theme or PrestaShop, do a few things.
- Download a copy of the theme folder to your computer or ask your host for one.
- Check whether the store runs on a child theme. If not, create one before the update, not after.
- Read the theme author's changelog. If they changed a file you override in the child theme, your copy may need a fix.
- Update on a test copy of the store first, if you have one.
- After the update, go through your list of changes and check each one on the site.
How do you protect your changes in a conversation with the chat?
You ask for a child theme before changing anything in the look. Your chat (Claude or ChatGPT) checks the current theme and creates a child theme. Once you turn it on, the chat saves changes there, with a copy of every file.
You: After the theme update, the free delivery text disappeared from the product page. Bring it back so it does not disappear in the next update.
Your chat: The active theme is Lumo 3.2, with no child theme. I suggest creating a child theme lumo-child first. I won't turn it on myself, you do that in Design > Theme & Logo.
Before saving you'll see the difference in the file, and the file gets a backup copy.
Card status: waiting for your “yes”Once you turn it on, I'll add the text to the product page template in it:
old version: (no text under the price)
new version: Free delivery on orders over €50
For changes to theme files you need TellMyShop Pro and the Theme switch, which you turn on in the module panel. The switch lasts 24 hours and requires a database backup made the same day. You can undo a file change from its copy. Creating the child theme is not undone from the change history. You remove a theme you no longer need in the back office. TellMyShop Free does not read theme files, that only works in Pro.
How to phrase such a task is shown in the use cases protecting theme changes before an update and restoring a theme file from a copy.
Questions and answers
Can I recover my changes after a theme update?
Often yes, if a copy of the files from before the update exists. Look for it in your host's backups, in the files on the computer of the person who made the changes, or in the package of the old theme version. If there is no copy, the changes have to be recreated from screenshots, a web archive or the developer's memory.
Why does a theme update wipe my changes?
Because the update replaces the theme files with new versions from the author. A file you changed goes back to the author's version along with the bug fixes. The update does not know which lines were yours. That is why changes belong in a child theme, which an update of the parent theme does not touch.
Will a child theme slow the store down?
It should not. A child theme is a small folder with a configuration file and only the files you change. PrestaShop takes the rest from the parent theme. After turning it on, check the home page, a product page and the cart, because in the store settings it is formally a different theme.
Do changes in modules also disappear after an update?
Yes, if they were made in the module's files. A module update replaces its files just like a theme update. You change a module's look safely in a copy of its template inside the theme, ideally the child theme. PrestaShop then uses the copy, and the module update leaves it alone.
Will the chat recover my old files?
Only the ones it changed itself. Before every file save the chat makes a copy. Copies are kept for 90 days, and the five newest of each file are always kept. Changes made by hand over FTP or by a developer are not in those copies. Then you need a backup from your host or from the person who made them.
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