How do I make an external URL open on a new tab? When I try putting a link like &lt;a href="http://www.example.com/" target="_blank"&gt; on the link path, I get the following error message:  


  The path '//www.example.com/" target="_blank">' is either invalid or you do not have access to it.   


Is there a way to have the external URL opened in a new tab?
If you can target your menu tag with jquery using its ID you can put something like this in an JS file that you'll add in your theme via your_theme.info

Drupal.behaviors.externalMenu = function(context, settings) {
    $('#menu_id').attr('target', '_blank');
};


Or you can use the Menu attributes module.