‘Page could not be reached’ error- facebook ‘like’ – Solution

Some WordPress and Joomla sites have a problem where the template or URL of the page/site causes an error in facebook. The issue usually manifests in two ways.

1. The Facebook ‘Like’ refuses to work. The usual error seen on hitting the ‘like’ button is:
   

   The page at XXXX could not be reached

2. Facebook fails to show the thumbnails and meta information, of any link posted to facebook, from the affected site