Upgrade PrestaShop to 9: a checklist for before and after the update

What changes in PrestaShop 9?

PrestaShop 9 is a major version and changes the foundations of the store. In the PrestaShop 9 announcement the PrestaShop team lists, among other things, a newer Symfony version, support for newer PHP and the new Hummingbird theme. For a store owner the consequences matter: different server requirements and modules that have to be adapted to the new version.

Not every change will touch your store. But every module from a third-party author and every edit to the theme is a place you need to check. Problems after moving from 8 to 9 have been collected, for example, by Modules4Presta (in Polish).

What should you check before the upgrade?

Check six things before the upgrade and decide who is responsible for each.

The last row often gets skipped, which is a pity. Without a record of how things were, after the upgrade you cannot tell a new error from an old one that has sat in the log for months. How to back up files and the database is described in the backup documentation.

How does the upgrade itself work?

The update is done by the Update Assistant module from PrestaShop. Step-by-step instructions, with backup and restore, are in the documentation on updating from the back office.

1. Turn on the store's maintenance mode for the duration of the update, so customers do not place orders in the middle of it.
2. Update the test copy first. Check the cart, payments, emails and modules on it for a few days.
3. Install Update Assistant on the store and choose the target version.
4. Let the module make a backup. Do not turn this option off, even if you have a backup with your host.
5. Run the update and do not close the browser tab until it finishes.
6. Update the modules that have a version for PrestaShop 9, one at a time.
7. Turn off maintenance mode only after the checks in the list below.

Updating from very old versions, for example 1.6, is a separate topic. There you usually need a migration with a developer's help.

When should you plan the upgrade?

In a quiet period, on a working day, with time to spare for problems. Before the season, a sale or a big campaign, leave the store alone. A new version is not worth the risk in the week of your biggest sales.

Plan who will be on call as well. If a developer does the update, agree that they will answer reports over the following days. If you do it yourself, check beforehand how quickly your host's support reacts and whether they will restore a backup when you ask.

When an important module has no version for PrestaShop 9 yet, you have two options. You can wait for the author or find a replacement and test it on the store copy. Updating with an incompatible payment or delivery module is asking for trouble.

What should you check right after the upgrade?

Start with the customer's path, then move to the back office.

• The home page, a category, a product page, search and filters.
• The cart and a full test order, with every payment and delivery method.
• Customer emails: order confirmation, registration, password reset.
• The error log in Advanced Parameters > Logs, compared with the state before the update.
• The look of modules that have edits in the theme.
• Debug mode off, cache cleared.

If something stopped working, read how to disable a PrestaShop module safely. When the store shows a blank page, start with the plan in the article on the 500 error.

How does the chat help with the upgrade?

Your chat (Claude or ChatGPT) does not update PrestaShop. It runs a review before and after, so you have something to compare. In TellMyShop Free it reads the store's technical status and the PrestaShop and PHP versions. It also checks the list of modules with their versions and the error log from the last few days.