Does Magento 2.4.9 support PHP 8.4?

Question

Accepted Answer

PHP 8.4 runs Magento 2.4.9: the PHP constraint in the 2.4.9 composer.json includes PHP 8.4. Adobe’s official system requirements table, however, lists PHP 8.5 for 2.4.9, and Adobe only supports the combinations in that table. The 2.4.9 release notes also confirm that this release added official PHP 8.5 support. So for a supported 2.4.9 setup, plan for PHP 8.5 and treat PHP 8.4 as a stepping stone.

PHP versions in Adobe’s system requirements for the latest patch of each line:

2.4.6-p15: PHP 8.1 and 8.2.
2.4.7-p10: PHP 8.2 and 8.3.
2.4.8-p5: PHP 8.3 and 8.4.
2.4.9: PHP 8.5.

Source: Adobe Commerce system requirements, checked October 2026.

If you’re upgrading PHP separately from Magento: upgrade Magento first, then PHP within the same maintenance window. Doing PHP first on an older Magento breaks the framework (PHP 8.3+ deprecates things 2.4.6 still depends on). The exception: PHP 7.4 → 8.x is so foundational that some teams do PHP first on a heavily-patched older Magento, then Magento, but it’s riskier.