Steps to reproduce the issue

1. Set up a Joomla 5.x site with session handler set to "database"
2. Enable the "System - Session Garbage Collector" plugin
3. Schedule the com_plugins.task.sessiongc task using Joomla Scheduler
4. Set the task to run daily via CLI using:
   php cli/joomla.php scheduler:run --all
5. Let the session table grow over time with inactive sessions
6. Check the number of records in the #__session table
7. Now manually execute the same task via the Joomla backend (Scheduler > Tasks > Execute now)
8. Check the #__session table again

Expected result

Expired session records (older than the configured lifetime) are removed from the #__session table both when:

• The task is executed via the backend
• The task is executed via the CLI (cron)

Actual result

• When executed via the backend, the task successfully removes expired sessions.
• When executed via CLI, the task is marked as "Completed" in the execution log, but expired session records remain in the database — the session cleanup does not occur.

System information (as much as possible)

• Joomla version: 5.x (tested on 5.0.3 and 5.1.0)
• PHP version: 8.2
• Session handler: database
• CLI command: php cli/joomla.php scheduler:run --all

Additional comments

It appears that the session cleanup (gc()) relies on an active session handler context, which is not properly initialized in CLI mode. This causes Factory::getSession()->getHandler()->gc() to have no effect during CLI runs.

The issue is not configuration-related: the same task, with no changes, works as expected via the backend.

Please consider:

• Initializing the session handler explicitly in this context
• Or falling back to direct database cleanup when session handler is not active in CLI

This issue affects Joomla administrators relying on the Scheduler system as a unified automation method.