index.php path doesn't seem to work – no input file specified

That sounds like a .htaccess file error.

Go to your settings/permalinks to rebuild your permalinks and then try again.

Additionally, if you want to eliminate any 404 errors, you could add this to your functions.php file. It will redirect all 404s to an actual existing page (change the /new-location-page-here/ page URL below to the one you want them redirected to):

add_action('template_redirect','personal_404_redirect_override',1);
function personal_404_redirect_override(){
      global $wp;
            if(!is_admin() && is_404()){
                  wp_redirect('/new-location-page-here/',301);
                  exit;
            }
      }
}

Hope this helps,
Regards,
Don