Upgrade from Joomla 3 to 4 (real example with troubleshooting steps)

Steps to upgrade from Joomla 3 to 4: Take a backup, install minimum version Joomla 3.10.x. Update all Joomla extensions and template. Change Joomla update channel, run Joomla 4 Pre-Update check and troubleshoot Joomla 4 upgrade Issues.

Steps to update Joomla 3 to 4

Backup your website
Install Joomla 3.10.x
Update Joomla Extensions
Update Website Template
Change Joomla update channel
Run Joomla 4 Pre-Update Check
Troubleshoot Joomla 4 Upgrade Issues
Upgrade to Joomla 4
Re-enable Disabled Plugins
Update Extensions to Joomla 4
Check Joomla 4 Post Installation Messages
Check your website front end

1. Backup your website

Take a backup of your website before making any changes

2. Install Joomla 3.10.x

Upgrade to Joomla 3.10.x first before migrating to Joomla 4

3. Update Joomla Extensions

Update all Joomla extensions and uninstall any extensions you are no longer using

Extensions - Manage - Update

Click Update

4. Update Website Template

Check if your template has a Joomla 4 version and update it

Check your current template version

Extensions - Templates - Templates

Note the current template version

Update Joomla Template

Extensions - Manage - Install

Upload package file - browse for the new template .zip file

Joomla website template has been updated

5. Change Joomla update channel

Set the Joomla update channel to Joomla next

System - Global Configuration

Joomla Update
Update Channel - Joomla Next

Save & Close

6. Run Joomla 4 Pre-Update Check

Components - Joomla update

Joomla 4 Pre-Update Check Overview

The pre-update checker shows any components that are not compatible with Joomla 4
You'll need to update or uninstall them before upgrading to Joomla 4
Check each extension carefully. Some can be updated, others will need to be removed or disabled during the upgrade.

Check the live update tab for a list of plugins that could cause problems with the upgrade

For some extensions, you might need to install the last available Joomla 3 version and then the first Joomla 4 compatible version

Incompatible plugins may need to be disabled during the upgrade and the Joomla 4 version installed after the update has completed

The Live update tab lists plugins that might cause problems with the upgrade to Joomla 4

Click "More Detail" to get the Joomla 4 compatible versions

In this example the "Regular Labs - Modals" extension needs to be updated for Joomla 4

7. Troubleshoot Joomla 4 Upgrade Issues

Outdated Akeeba extensions detected

To fix this issue, you'll need to run the Akeeba Magic Eraser to clean-up old versions of Akeeba components

Click the link for Magic Eraser and download the .zip file from Github

Extensions - Manage - Install
Upload Package File - browse for the Magic Eraser .zip file

Magic Eraser has removed an obsolete extension and folder

You can find more details about Akeeba components and Joomla 4 here

Joomla 4 is around the corner
https://www.akeeba.com/news/1747-joomla-4-is-around-the-corner.html

The following plugins could cause problems during the upgrade

System - Akeeba extensions version check
System - Helix3 Framework
System - Helix Ultimate Framework
System - Regular Labs - Modals
System - Joomlashack Extension Support
System - Regular Labs Library
System - SP Cookie Consent
System - SP PageBuilder
System - SP Page Builder Pro Updater