JoomlaUpgradePack

How to fix Jupgrade Migrating undefined error when upgrading to Joomla 2.5

2012-11-05 by Alessandro Pasotti filed under Joomla. Recently I had an error message while migrating and old Joomla! 1.5 site to the new Joomla! 2.5, jupgrade failed with “Migrating undefined” error. After digging in the code I found a solution: You have to edit two files: jupgrade/installation/models/configuration.php jupgrade/installation/models/database.php and insert the following line near the top of the script: require_once JPATH_ROOT.'/jupgrade/libraries/cms/model/legacy.php'; When done (after the failed upgrade), you can retry the migration checking the following options in Jupgrade configuration:ex

Original article: https://www.itopen.it/fixing-jupgrade-migrating-undefined-error-when-upgrading-joomla/

JUPGRADE PRO Packages

Install it in a Joomla 2.5 or Joomla 3.x website and retrive data from old 1.0, 1.5 and 2.5 websites. Is better using database method.

Upgrading Versions

https://docs.joomla.org/Portal:Upgrading_Versions

Migration

The documentation below is a funnel starting with Why Migrate. Simply follow the buttons at the bottom of each page that are applicable to you. The Self Assessment will help you determine if doing the migration is within your skill set. Please don't skip the Planning pages as they include important information for your migration.

• Why Migrate

• Migration Step by Step Self Assessment

• Planning for Migration

• Updating a Joomla CMS 3.x.x Installation

  • Updating Joomla CMS 3.x.x (Update Method) recommended method
  • Updating Joomla CMS 3.x.x (Install Method)

• Updating a Joomla CMS 2.5.x Installation EOS

  • Updating Joomla CMS 2.5.x (Update Method) recommended method
  • Updating Joomla CMS 2.5.x (Install Method)

Migration

The documentation below is a funnel starting with Why Migrate. Simply follow the buttons at the bottom of each page that are applicable to you. The Self Assessment will help you determine if doing the migration is within your skill set. Please don't skip the Planning pages as they include important information for your migration.

• Why Migrate
• Migration Step by Step Self Assessment
• Planning for Migration

Migration 1.5 to 3.x

• Planning Migration - Joomla 1.5 to 3
• Joomla 1.5 to 3.x Step by Step Migration
• Migrating a Template from Joomla 1.5 to 3.x

Migration 2.5 to 3.x

• Planning for Mini-Migration - Joomla 2.5 to 3.x
• Joomla 2.5 to 3.x Step by Step Migration
• Joomla 2.5 to 3.x Common Migration Errors

Migration 3.10 to 4.x

• Planning for Mini-Migration - Joomla 3.10 to 4.x
• Joomla 3.10 to 4.x Step by Step Migration
• Joomla 3.10 to 4.x Common Migration Errors

Update 4.4 to 5.x (new)

• Pre-Update Check
• Planning for Update - Joomla 4.4.x to 5.x
• Pre-Update Check
• Planning for Update - Joomla 4.4.x to 5.x

Update 5.x to 6.x (latest - October 2025)

• Joomla 6.0 Official Announcement
• Joomla 6.0 Release Notes (GitHub)
• Joomla 6 Official Site
• Joomla Developer Manual (v6.0)
• Download Joomla 6.0

Quick Upgrade/Update Instructions

Pre-Update Checklist

Before upgrading your Joomla site, complete these essential steps:

1. Backup Everything

   • Create a full backup of your website files
   • Export and backup your database
   • Store backups in a safe location (local + cloud recommended)

2. Check Compatibility

   • Review the Pre-Update Check in your Joomla admin panel
   • Verify all extensions are compatible with the target version
   • Check your template compatibility
   • Review PHP version requirements (Joomla 6 requires PHP 8.1+)

3. Test Environment

   • Set up a staging/test site with a copy of your production site
   • Test the upgrade on staging first
   • Verify all functionality works after upgrade

4. Read Release Notes

   • Check what's new and what's changed
   • Review deprecated features
   • Note any breaking changes

Update Steps (Joomla One-Click Update)

1. Access Joomla Update Component

   • Log in to your Joomla Administrator panel
   • Go to System → Update → Joomla

2. Run Pre-Update Check

   • Review all warnings and errors
   • Fix any issues before proceeding

3. Start Update

   • Click "Install the Update" button
   • Wait for the update to complete (do not close browser)

4. Post-Update Tasks

   • Clear Joomla cache (System → Clear Cache)
   • Clear browser cache
   • Check frontend and backend functionality
   • Test all extensions and custom features
   • Fix any template or extension issues

Important Notes

• ⚠️ Joomla 6 Upgrade Requirement: You must be on Joomla 5.4.0 or higher before upgrading to Joomla 6. If you're on an older version (5.3.x or earlier), first update to Joomla 5.4.0, then proceed to Joomla 6.
• Joomla 3.x to 4.x or 5.x: Major migrations require a migration path (not simple update). Follow the step-by-step migration guides.
• Minor Updates (e.g., 5.3 to 5.4): Can be done via one-click update
• Major Updates (e.g., 5.x to 6.x): Review breaking changes and test thoroughly
• PHP Requirements: Joomla 6 requires PHP 8.1 or higher
• Always backup before any update!

Troubleshooting

If update fails:

• Restore from backup
• Check server requirements (PHP version, extensions)
• Review error logs (administrator/logs/)
• Increase PHP memory limit and execution time
• Disable all third-party plugins temporarily
• Seek help in Joomla Forum