Moving a live WooCommerce store from PHP 7.4 to current

WooCommerce’s server requirements for version 10.8 and later list PHP 8.3 or greater, tested up to PHP 8.4, with MySQL 8.0 or greater, or MariaDB 10.6 or greater, and WordPress 6.9. The same page says it still works on PHP 7.4 and later, MySQL 5.6 and later, or MariaDB 10.4 and later, but that those are past end of life and may create security risks.

So core may well run, and that’s the risk. An old store can look fine while its PHP gets no fixes, and while each newer plugin release quietly drops support for it. PHP 8.3 has security fixes until 31 December 2027 and PHP 8.4 until 31 December 2028.

Write down what you have before you change anything.

wp --info
wp core version
wp plugin list --fields=name,status,version,update
wp theme list --fields=name,status,version,update

For each plugin, record who makes it, whether it is still maintained, and what it does for the business. A plugin with no release in years is your likeliest problem. Include anything custom, such as a child theme or a code snippets plugin. Also list everything outside WordPress that touches the store: payment gateways, shipping, feeds, and any ERP integration.

On the store we look after, backups run every two hours to S3-compatible storage, with tested restores. You may not need that frequency, but you do need a restore you have actually carried out. A store takes orders all day, so also decide how much order data you could stand to lose, since that sets the schedule.

Use the same server setup with the target PHP version. Then make it safe: turn off outgoing email, switch payment gateways to test mode, and point any integration at a sandbox. A staging site that sends real emails or real orders into your ERP will have you apologising to customers.

Turn on logging on staging, and browse and buy. What you are looking for on this jump is covered in our PHP upgrade matrix. On WooCommerce sites, the usual sources are:

• The PHP 8.0 removals and type errors. Things that used to warn can now throw, and that can take down the whole checkout, not only one widget.
• Loose comparisons in custom pricing, shipping or discount rules. These don’t error. Test them with real cases and compare totals with the live store.
• Dynamic property and null deprecations from 8.1 and 8.2. These only make noise for now, but the volume can be large in older plugins.

Change one layer at a time so that when something breaks, you know which change did it. A common order is to update plugins and theme while still on the old PHP, as far as they allow, then change PHP, then update whatever needed the newer version. Replace abandoned plugins rather than patching them, unless the plugin is small and you will take on owning it.

On our client’s store this happened progressively within the maintenance engagement, with PHP, plugins and theme all brought current over time. Moving in smaller steps costs more calendar time, and it means there’s never one large, risky release.

• Guest and account checkout, with each payment method and with a refund.
• Coupons, tax on each rate you use, shipping rules, and order emails.
• Variable products and stock changes after a sale.
• Scheduled jobs and any subscription renewals.
• The integration. If orders go to an ERP, confirm that a test order arrives with the right totals. Syncing orders at high volume covers what to watch.

• Choose your quietest hour, from your own order data rather than a guess.
• Take a fresh backup just before.
• Change PHP, clear caches, including OPcache, and place a real test order.
• Watch the error log and payment gateway dashboard for the rest of the day.
• Check WooCommerce’s webhook status and scheduled actions, since they can stall without anyone noticing.

The expensive part of this job is having let it build up. Once you are current, a release of PHP or WooCommerce is a small routine task. That is what a maintenance plan is for, and it’s how the Belgian store stays where it is. See WooCommerce maintenance for our plans. For systems beyond WooCommerce, see legacy PHP modernisation.