Steps to reproduce the issue

I'm not sure how the settings as a whole are causing the error, hence all the steps:

• Install Joomla_5.4.0-beta2-dev+pr.45696-Development-Full_Package.zip
• Disable Automated Updates and delete Installation folder
• Installed additional plg_system_autoupdatepreventer and enabled it
• 'Log Almost Everything' and 'Debug System' enabled
• Installed 'System - Alpha Update Server' 0.6.1 plugin
• Check with manual update 'Joomla Update to Joomla! 5.4.113 is available (twice needed)
  • Fixed Database structure
• Enable Automated Update

Expected result

No PHP warnings.

Actual result

For each enabling/disabling Automated Updates there is one line:

[25-Aug-2025 08:50:17 UTC] PHP Warning:  Array to string conversion in /var/www/joomla-test.heikol.de/public_html/libraries/src/HTML/HTMLHelper.php on line 327

System information (as much as possible)

First debug by inserting:

    326 
    327 if (is_array($url) || is_array($text)) {
    328  debug_print_backtrace();die();
    329 }

Results in

#0 /var/www/joomla-test.heikol.de/public_html/libraries/src/HTML/HTMLHelper.php(307): Joomla\CMS\HTML\HTMLHelper::link(Array, '...', '...')
#1 /var/www/joomla-test.heikol.de/public_html/libraries/src/HTML/HTMLHelper.php(195): Joomla\CMS\HTML\HTMLHelper::call(Array, Array)
#2 /var/www/joomla-test.heikol.de/public_html/administrator/components/com_joomlaupdate/tmpl/joomlaupdate/update.php(38): Joomla\CMS\HTML\HTMLHelper::_('...', Array, '...', Array)
#3 /var/www/joomla-test.heikol.de/public_html/libraries/src/MVC/View/HtmlView.php(416): include('...')
#4 /var/www/joomla-test.heikol.de/public_html/libraries/src/MVC/View/HtmlView.php(204): Joomla\CMS\MVC\View\HtmlView->loadTemplate(NULL)
#5 /var/www/joomla-test.heikol.de/public_html/administrator/components/com_joomlaupdate/src/View/Joomlaupdate/HtmlView.php(273): Joomla\CMS\MVC\View\HtmlView->display(NULL)
#6 /var/www/joomla-test.heikol.de/public_html/administrator/components/com_joomlaupdate/src/Controller/DisplayController.php(88): Joomla\Component\Joomlaupdate\Administrator\View\Joomlaupdate\HtmlView->display()
#7 /var/www/joomla-test.heikol.de/public_html/libraries/src/MVC/Controller/BaseController.php(730): Joomla\Component\Joomlaupdate\Administrator\Controller\DisplayController->display()
#8 /var/www/joomla-test.heikol.de/public_html/libraries/src/Dispatcher/ComponentDispatcher.php(143): Joomla\CMS\MVC\Controller\BaseController->execute('...')
#9 /var/www/joomla-test.heikol.de/public_html/libraries/src/Component/ComponentHelper.php(361): Joomla\CMS\Dispatcher\ComponentDispatcher->dispatch()
#10 /var/www/joomla-test.heikol.de/public_html/libraries/src/Application/AdministratorApplication.php(150): Joomla\CMS\Component\ComponentHelper::renderComponent('...')
#11 /var/www/joomla-test.heikol.de/public_html/libraries/src/Application/AdministratorApplication.php(205): Joomla\CMS\Application\AdministratorApplication->dispatch()
#12 /var/www/joomla-test.heikol.de/public_html/libraries/src/Application/CMSApplication.php(304): Joomla\CMS\Application\AdministratorApplication->doExecute()
#13 /var/www/joomla-test.heikol.de/public_html/administrator/includes/app.php(58): Joomla\CMS\Application\CMSApplication->execute()
#14 /var/www/joomla-test.heikol.de/public_html/administrator/index.php(32): require_once('...') 

Additional comments

Found in testing #45964