core-bundle/src/Resources/contao/library/Contao/Message.php
public static function reset()
	{
		$session = System::getContainer()->get('session');

		if (!$session->isStarted())
		{
			return;
		}

		$session->getFlashBag()->clear();
	}
public static function reset()
	{
		$session = System::getContainer()->get('session');

		if (!$session->isStarted())
		{
			return;
		}

		$session->getFlashBag()->clear();
	}
Reset the message system