Joomla 3 to Joomla 5 Migration

Joomla 3 to Joomla 5 Site Migration

Joomla 3 reached EOL in August 2023. Joomla 4 and 5 use new architecture (PSR-4, Namespaces, DI Container) incompatible with Joomla 3 extensions. Migration requires updating all extensions and rewriting custom code.

Migration Strategy

Option 1: Staged Update — J3 → J4 → J5. Pre-Update Check tool helps identify incompatible extensions at each step.

Option 2: Clean J5 Installation — install J5 from scratch, migrate only content and configuration. Template and extensions — new compatible versions. Faster if many outdated extensions.

Pre-Update Check

Components → Joomla! Update → Pre-Update Check. Shows:

• Extensions without J4/J5-compatible version
• Deprecated PHP functions in custom code
• Obsolete database tables

J3 → J4: Direct Update

# 1. Via web updater (if all extensions compatible)
# Components → Joomla! Update → install Joomla 4.x

# 2. Fix incompatible extensions before updating
# Find J4-compatible versions or remove

# 3. After update
php cli/joomla.php database:update

J4 → J5: Update

# Joomla 5 requires PHP 8.1+
php -v  # check version

# Update via updater
# Components → Joomla! Update → Joomla 5.x

Content Migration on Clean Installation

// Export content from J3
// Use com_content data export or direct SQL dump

// jos_content table structure is identical in J3/J4/J5 — direct import works
// But: some fields changed, need verification

// Import via CLI:
php cli/joomla.php import:content --file /tmp/content-export.sql

Templates: Joomla 3 → 5

J3 templates are not compatible with J5. J5 requires templates based on new Bootstrap 5 API or Cassiopeia.

Popular template builders with J5 support:

• Helix Ultimate — open source
• Astroid Framework
• YOOtheme Pro

Custom Extension Migration

Custom Joomla 3 components require refactoring:

// J3 (outdated):
$db = JFactory::getDbo();
$user = JFactory::getUser();
$app = JFactory::getApplication();

// J5 (correct):
$db = \Joomla\CMS\Factory::getDbo();
$user = \Joomla\CMS\Factory::getApplication()->getIdentity();
$app = \Joomla\CMS\Factory::getApplication();

// Namespaces
namespace MyCompany\Component\Catalog\Site\Controller;
use Joomla\CMS\MVC\Controller\BaseController;

Timeline