OpenCart 3 or OpenCart 4? Which to Use in 2026

For most existing stores, the honest answer is to stay on OpenCart 3 and update to the latest 3.0 release, because it runs on current PHP and your extensions keep working. OpenCart 4 makes sense for a fresh build that needs few extensions. Moving an established store from 3 to 4 is a rebuild of its extensions, not an update, so do it only when you have a reason to.

Both versions are still being released. The latest are 3.0.5.1 and 4.1.0.4, both released in August 2026.

The main difference: extensions

OpenCart 4 is structured differently from OpenCart 3, so extensions and themes written for 3 don't run on 4 without being rewritten. That's the single biggest factor in the decision, because most established stores rely on a handful of extensions for payments, shipping, feeds and features the shop can't do without.

OpenCart 4.0 also dropped OCMOD, the system OpenCart 3 extensions use to modify OpenCart's own files, in favour of events, which let extensions hook into OpenCart without editing its files. From 4.1, OpenCart's code supports OCMOD modifications again, but extensions written for 3 still need rewriting for 4.

Antropy, a UK OpenCart agency, wrote in September 2025 that it still recommends OpenCart 3: it has the widest range of extensions, most extensions for earlier 3.0 releases still work on the latest one, and extensions for OpenCart 4 weren't yet as widely available. They also said OCMOD was being reintroduced in OpenCart 4 but didn't yet work at the time. That's one agency's view, and the best test for your store is to list the extensions it depends on and check whether each exists for OpenCart 4.

PHP versions

PHP is the other half of the decision, because your host decides which PHP versions you can use.

OpenCart version	PHP versions
Before 3.0.3.9	Not compatible with PHP 8
3.0.3.9 to 3.0.4.1	PHP 7.3 to 8.3
3.0.5.0	PHP 8.1 to 8.4
4.1.0.0 to 4.1.0.3	PHP 8.0.2 or newer
4.1.0.4	PHP 8.1 or newer

The latest 3.0 release, 3.0.5.1, needs at least PHP 8.1. So staying on OpenCart 3 doesn't mean staying on old PHP, as long as you're on a recent 3.0 release. If your store is older than 3.0.3.9 and showing errors after a PHP upgrade, see OpenCart 3 PHP 8 errors.

Which should you choose?

Stay on OpenCart 3 and update to the latest 3.0 release if your store is established, relies on extensions, and works well apart from PHP warnings or an old version. This is the right answer for most stores. You keep your extensions, theme, admin and data, and you get current PHP support.
Choose OpenCart 4 for a fresh build if you're starting a new store, need only a few extensions, and can confirm those extensions exist for your exact OpenCart 4 version before you start.
Move an existing store to OpenCart 4 only if there's a reason that outweighs rewriting or replacing every extension and the theme, such as a rebuild you were planning anyway.
Leave OpenCart altogether if the store needs rebuilding anyway, the extensions you depend on are abandoned, or you'd rather not manage updates and hosting yourself. WooCommerce or Shopify can be the better long-term home for some shops; see moving from OpenCart to WooCommerce or Shopify.

Before you change anything

Back up the files and the database first. OpenCart's own Backup / Restore, under System, Maintenance, only covers the database, so take a copy of the files through your host as well.

Then make the change on a copy of the store, not the live shop. Check every extension, place a test order, check your order emails and the admin, and only then repeat it on the live store.

If you'd like help deciding, or with the update itself, see OpenCart fixes. Updating to the latest 3.0 release, moving to OpenCart 4 and PHP 8 work are all quoted before I start.