Hi there is some issues with Joomla 6 and disable the plg_behaviour_compat6 ( Joomla 6.0.3, php 8.4.18) latest Helix Ultimate. Pls test, investigate and report back.

"Attempted to load class "Helper" from namespace "HelixUltimate\Framework\Platform".
Did you forget a "use" statement for another namespace?"

Report error crasched fontpage with Maximus report and debug on:

Symfony\Component\ErrorHandler\Error\ ClassNotFoundError
in /var/www/vhosts/site.com/httpdocs/templates/shaper_helixultimate/error.php (line 19)

use Joomla\CMS\Uri\Uri;
use Joomla\CMS\Language\Text;
$app = Factory::getApplication();
$doc = Factory::getDocument();
$template = Helper::loadTemplateData();
$params = $template->params;
$fontCSS = '';
function addGoogleFont($fonts)
{

require() in /var/www/vhosts/site.com/httpdocs/libraries/src/Document/HtmlDocument.php (line 734)
HtmlDocument->_loadTemplate() in /var/www/vhosts/site.com/httpdocs/libraries/src/Document/HtmlDocument.php (line 788)
HtmlDocument->_fetchTemplate() in /var/www/vhosts/site.com/httpdocs/libraries/src/Document/HtmlDocument.php (line 625)
HtmlDocument->parse() in /var/www/vhosts/site.com/httpdocs/libraries/src/Document/HtmlDocument.php (line 643)
HtmlDocument->render() in /var/www/vhosts/site.com/httpdocs/libraries/src/Document/ErrorDocument.php (line 139)
ErrorDocument->render() in /var/www/vhosts/site.com/httpdocs/libraries/src/Error/Renderer/HtmlRenderer.php (line 70)
HtmlRenderer->render() in /var/www/vhosts/site.com/httpdocs/libraries/src/Exception/ExceptionHandler.php (line 142)
ExceptionHandler::render() in /var/www/vhosts/site.com/httpdocs/libraries/src/Exception/ExceptionHandler.php (line 76)
ExceptionHandler::handleException() in /var/www/vhosts/site.com/httpdocs/libraries/src/Application/CMSApplication.php (line 350)
CMSApplication->execute() in /var/www/vhosts/site.com/httpdocs/includes/app.php (line 58)
require_once('/var/www/vhosts/site.com/httpdocs/includes/app.php') in /var/www/vhosts/site.com/httpdocs/index.php (line 51)
Error

Class "Joomla\CMS\Filesystem\File" not found