Treat the upgrade as a project
Moving from PrestaShop 8 to 9 affects PHP compatibility, modules, themes, overrides and external integrations. A working homepage does not prove that checkout, shipping or back-office operations are healthy. Set measurable success criteria for orders, catalogue integrity and search visibility.
Inventory and recoverable backups
Record the exact core release, PHP runtime, SQL engine, active modules, cron jobs and custom code. PrestaShop 9.0 requires PHP 8.1 or newer and supports PHP up to 8.4 in its published compatibility range. Keep a full file-and-database backup and test restoration outside production. A backup that has never been restored is not an established recovery plan.
Choose an upgrade path
The official Update Assistant offers upgrade, backup and restore workflows. It cannot certify every third-party module. Depending on technical debt, a controlled rebuild with data migration may be preferable. Compare business downtime, custom features, catalogue scale and the effort required to validate data before choosing.
Verify linked business data
Audit combinations, stock, prices, images and language/shop relations, then customers, addresses, carts, orders, payments, customer service records and module tables. Compare counts but also inspect representative cases: discounted orders, multiple addresses, packs and out-of-stock variants. Those relational cases often expose migration gaps.
Protect search visibility
Map important product, category, CMS and editorial URLs. Keep established paths when feasible; otherwise configure direct permanent redirects to equivalent pages. Validate canonical tags, internal links, hreflang annotations, XML sitemaps and 404 reporting in Search Console. Avoid bulk redirects to the homepage.
Rehearse checkout and the cutover
Run scripted tests for mobile navigation, cart updates, address selection, tax, carriers, payment, invoices, emails and order statuses. Freeze old data at an agreed point, reconcile the final delta and retain a tested rollback. Watch payment logs, API synchronisations and crawl errors after launch.
Review checklist
- Test backups and restores
- List modules and overrides
- Reconcile customer/order data
- Test checkout and payments
- Check legacy URLs
Related guides on Concepty
- PrestaShop redesign: preserve SEO during a site rebuild
- Custom PrestaShop modules: from business need to safe deployment
- E-commerce technical audit: what to check before sales suffer
Practical next steps
Before making changes, record your versions, business constraints and reproducible issues. I can help with PrestaShop development, or you can describe your project on the contact page. The goal is a tested, maintainable improvement rather than another unnecessary dependency.