n Joomla!, the most common reason for this error involves a lack of content - a menu item was supposed to be linked to an article, but the article no longer exists. For instance, sometimes an article is created and linked to a menu item, but then the category under which the article was saved somehow gets deleted. In this example, the menu item still exists, but there is no longer an article to view, and the user receives a 404 error. To fix this specific issue, you ll have to create some content and link it to the menu item. The first step is to go to your Article Manager.