When we try to change the friendly URL of Joomla from the control panel, we can show the following error when clicking on any link on the Web.
The requested URL / was not found tudireccion on this server.
Additionally, a 404 Not Found Error was Encountered while trying to use an ErrorDocument to handle the request.
The problem is that you have renamed the htaccess.txt file to. Htaccess and then to enable friendly URLs in Joomla, is a problem because the system can not handle the rewrites and fail the URLS.
So all you have to do is rename the file and everything worked properly.