Switching Magento 1.x to PHP 7.4

This page describes the legacy compatibility work that is used to help Magento 1.x stores move from an older PHP runtime to PHP 7.4 (and afterward to current versions).

When this reference applied

The work was intended for a store whose hosting provider was dropping PHP 5.6 or support while the Magento 1.x core or installed extensions still depended on that runtime. Compatibility had to be checked for the complete store, not only for the Magento core.

For an actively maintained Magento 1 installation, review the OpenMage upgrade path first. Do not treat the historical PHP 7.4 compatibility approach as a current security or support baseline. Further upgrade to current PHP 8.3 and PHP 8.4 is strongly recommended especially taking into account recent PHP2Shell vulnerability. 

Our work process

The original engagement followed a staged workflow:

1. The store owner submitted the request and provided the relevant context.
2. We reviewed the server, code and Magento state.
3. We copied the code to our staging environment (or provided stage server if requested) using the existing PHP version.
4. We prepared and applied the compatibility changes for the Magento core and extensions.
5. We switched the staging environment to PHP 7.4 (and later to newer versions).
6. We checked for known post-change issues and fixed problems found during the review.
7. The store owner verified the staging store before production deployment.
8. We deployed the approved changes and switched the production runtime.

The exact compatibility work depended on the Magento version, installed extensions, hosting environment and available staging workflow.

Current next step

If you maintain a legacy Magento store and need to understand its options, request an assessment. Include the current Magento or OpenMage version, PHP version, hosting context and the problem you are trying to solve. Do not send passwords or private keys through the form.