I had exactly the same problem a week or so ago - turns out it was my .htaccess file: see https://www.sitepoint.com/community/t/codeigniter-3-and-cgi-fastcgi-solved/223069.
I had exactly the same problem a week or so ago - turns out it was my .htaccess file: see https://www.sitepoint.com/community/t/codeigniter-3-and-cgi-fastcgi-solved/223069.