Hi there!

Thanks for reaching out.

I hope you have followed the Joomla migration guide before proceeding with the upgrade:

https://guide.joomla.org/user-manual/migration/joomla-5-to-6-planning-and-upgrade-step-by-step

To assist you better, could you please share your environment details, including:

• PHP version
• Template name and version

I also tried accessing the provided URL, but the site is not reachable from my end.

Once we have these details, we will be happy to look into the issue further.

Best regards,

Hello, thank you for the feedback.

1. Regarding URL access: due to company policies, access is restricted to Brazilian IP addresses, and Administrator access is prohibited unless originating directly from the company's physical premises. I apologize for this. I have been working with Joomla for over 20 years; in this case, there may be a specific issue I am unable to identify. Updates from Joomla 4 to 5 work normally. Updating from 5 to 6 with other templates works normally.
2. Regarding the specific items: Joomla! 5.4.6 Stable [ Kutegemea ] 26-May-2026 16:00 GMT PHP Version = 8.3.12 Database type: mysql Database version: 10.6.22-MariaDB-0ubuntu0.22.04.1-log shaper_helixultimate Helix Ultimate - 2.2.6 Site theme: Cassiopeia 1.0 SP PageBuilder 6.6.2

In the Pre-update Check for Joomla 6.1.1, the following are the only alert notes listed: Plugin Extensions

1. System - SP PageBuilder (Potentially serious issues. ) Installed Version 6.6.2 (No Compatibility Information)
2. System - SP Page Builder Pro Updater (Potentially serious issues. ) Installed Version 6.6.2 (No Compatibility Information)

Hello,

It is a bit difficult to investigate this further without backend access, especially since you have already followed the official documentation.

Just to confirm, could you please make sure that the Behaviour - Backward Compatibility 6 plugin is enabled?

Regarding the warnings related to SP Page Builder shown in the Joomla 6.1.1 Pre-update Check, those can be ignored and you can proceed with the update.

From my side, I have tested Helix Ultimate with SP Page Builder on Joomla 6.x, and the environment you mentioned should not cause any compatibility issues.

The error is usually caused by an extension/template that still calls JFactory directly, which is no longer available when backward compatibility is disabled.

Make sure all third-party extensions, templates, and plugins are updated to their latest Joomla 6-compatible versions.

Please let me know if you face any further issues.

Best regards,

Hello, I understand that it’s difficult to help without access. I really do need your help, as I have sites with a lot of content that need this update, and rebuilding the site from scratch is out of the question. I’ll create a copy of the site on my personal server for you to access, since the company network blocks access from external IPs.

I managed to do it; by disabling it—even with the front-end error—I was able to update Joomla.