Emcent – PHP Consulting & Coaching

Author: Guido Faecke | Date: Dec 6, 2025 | Categories: PHP, Migration, Doctrine, Mezzio

1. Assess Your Current Environment

Start by auditing your current PHP environment:

Check PHP version: php -v
List all installed extensions: php -m
Identify deprecated functions and features in PHP 5.6
Verify your database driver versions, especially for DB2 or MySQL

2. Update Dependencies

Upgrade libraries and frameworks to versions compatible with PHP 8+:

Doctrine ORM → ensure at least v2.15 for PHP 8 compatibility
Mezzio / Laminas packages → upgrade to latest stable releases
Any composer packages → run composer outdated and review

3. Codebase Modernization

Refactor legacy code where needed:

Replace mysql_* functions with PDO or mysqli
Replace short array syntax array() with []
Remove deprecated functions and features
Add type hints, strict types, and modern OOP patterns where feasible

4. Testing & Static Analysis

Before running on PHP 8+, use automated tools:

Static analysis: PHPStan and/or Psalm
Code style checks: PHP_CodeSniffer
Unit and integration tests: ensure coverage for critical paths

5. Database Considerations

DB2 and other databases may need adjustments:

Check charset and collation compatibility
Optimize queries if performance issues arise
Test stored procedures and triggers under new PHP drivers

6. Deployment Strategy

Safely roll out changes:

Use staging environment with PHP 8.4
Run full regression tests
Deploy incrementally and monitor logs

7. Post-Migration Monitoring

Once live, monitor performance and error logs:

Check for deprecation warnings and runtime errors
Monitor DB2 query performance
Ensure API endpoints remain functional

Following this checklist will help you migrate safely from PHP 5.6 to 8.4 while keeping your applications stable and performant.