Attempted to load class "JFactory" from the global namespace.
Did you forget a "use" statement?

Symfony\Component\ErrorHandler\Error\ClassNotFoundError:
Attempted to load class "JFactory" from the global namespace.
Did you forget a "use" statement?

  at /home/dh_b0myteb/bergep.dmker.hu/templates/gridbox/error.php:11
  at require()
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Document/HtmlDocument.php:731)
  at Joomla\CMS\Document\HtmlDocument->_loadTemplate('/home/dh_b0myteb/bergep.dmker.hu/templates/gridbox', 'error.php')
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Document/HtmlDocument.php:785)
  at Joomla\CMS\Document\HtmlDocument->_fetchTemplate(array('template' => 'gridbox', 'directory' => '/home/dh_b0myteb/bergep.dmker.hu/templates', 'debug' => false, 'csp_nonce' => null, 'templateInherits' => '', 'params' => object(Registry), 'file' => 'error.php'))
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Document/HtmlDocument.php:622)
  at Joomla\CMS\Document\HtmlDocument->parse(array('template' => 'gridbox', 'directory' => '/home/dh_b0myteb/bergep.dmker.hu/templates', 'debug' => false, 'csp_nonce' => null, 'templateInherits' => '', 'params' => object(Registry), 'file' => 'error.php'))
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Document/HtmlDocument.php:640)
  at Joomla\CMS\Document\HtmlDocument->render(false, array('template' => 'gridbox', 'directory' => '/home/dh_b0myteb/bergep.dmker.hu/templates', 'debug' => false, 'csp_nonce' => null, 'templateInherits' => '', 'params' => object(Registry), 'file' => 'error.php'))
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Document/ErrorDocument.php:139)
  at Joomla\CMS\Document\ErrorDocument->render(false, array('template' => 'gridbox', 'directory' => '/home/dh_b0myteb/bergep.dmker.hu/templates', 'debug' => false, 'csp_nonce' => null, 'templateInherits' => '', 'params' => object(Registry), 'file' => 'error.php'))
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Error/Renderer/HtmlRenderer.php:70)
  at Joomla\CMS\Error\Renderer\HtmlRenderer->render(object(RuntimeException))
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Exception/ExceptionHandler.php:136)
  at Joomla\CMS\Exception\ExceptionHandler::render(object(RuntimeException))
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Exception/ExceptionHandler.php:73)
  at Joomla\CMS\Exception\ExceptionHandler::handleException(object(RuntimeException))
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Application/CMSApplication.php:336)
  at Joomla\CMS\Application\CMSApplication->execute()
     (/home/dh_b0myteb/bergep.dmker.hu/includes/app.php:58)
  at require_once('/home/dh_b0myteb/bergep.dmker.hu/includes/app.php')
     (/home/dh_b0myteb/bergep.dmker.hu/index.php:33)                

RuntimeException:
Failed to start the session because headers have already been sent by "/home/dh_b0myteb/bergep.dmker.hu/index.php" at line 1.

  at /home/dh_b0myteb/bergep.dmker.hu/libraries/vendor/joomla/session/src/Storage/NativeStorage.php:454
  at Joomla\Session\Storage\NativeStorage->start()
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Session/Storage/JoomlaStorage.php:313)
  at Joomla\CMS\Session\Storage\JoomlaStorage->start()
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/vendor/joomla/session/src/Session.php:396)
  at Joomla\Session\Session->start()
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/vendor/joomla/session/src/Session.php:327)
  at Joomla\Session\Session->has('user')
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Session/Session.php:194)
  at Joomla\CMS\Session\Session->get('user')
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Factory.php:372)
  at Joomla\CMS\Factory::getUser()
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Application/SiteApplication.php:570)
  at Joomla\CMS\Application\SiteApplication->initialiseApp()
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Application/SiteApplication.php:238)
  at Joomla\CMS\Application\SiteApplication->doExecute()
     (/home/dh_b0myteb/bergep.dmker.hu/libraries/src/Application/CMSApplication.php:306)
  at Joomla\CMS\Application\CMSApplication->execute()
     (/home/dh_b0myteb/bergep.dmker.hu/includes/app.php:58)
  at require_once('/home/dh_b0myteb/bergep.dmker.hu/includes/app.php')
     (/home/dh_b0myteb/bergep.dmker.hu/index.php:33)