PHP Version Upgrade Checklist

TL;DR

Explanation

PHP upgrade checklist: (1) Check current version EOL at php.net/eol. (2) composer outdated — update dependencies for new PHP version. (3) Run PHPCompatibility PHPCS to find incompatible code. (4) Run Rector for automated migration. (5) Enable E_ALL in dev and fix all notices/warnings/deprecations on current version first. (6) Set up staging environment with new PHP version. (7) Run full test suite. (8) Run with new version in shadow/canary mode. (9) PHP-FPM: update pool config for new version. (10) Monitor error logs after deployment. OPcache: clear after upgrade. JIT: reconfigure if used. Extensions: verify all needed extensions are available in new version.

Common Misconception

Why It Matters

Common Mistakes

• Upgrading PHP without first fixing all deprecation warnings on the old version.
• Not checking Composer dependency compatibility before upgrading.
• Forgetting to clear OPcache after PHP version change.

Code Examples

# Dangerous: direct prod upgrade without testing:
sudo apt-get install php8.3-fpm
sudo service php8.0-fpm stop
sudo service php8.3-fpm start

# Safe upgrade process:
# 1. Fix deprecations on current version:
php -d error_reporting=E_ALL -d display_errors=1 index.php

# 2. Check deps:
composer check-platform-reqs --php-version=8.3

# 3. Run Rector:
vendor/bin/rector process --dry-run

# 4. Test on staging with new PHP
# 5. Monitor for 24h, then prod rollout
# 6. Clear OPcache after deploy

References

• ↗ https://php.net/eol.php
• ↗ https://github.com/rectorphp/rector

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