It's because you have included a leading /
in your file path. The /
makes it start at the top of your filesystem. Note: filesystem path, not Web site path (you're not accessing it over HTTP). You can use a relative path with include_once
(one that doesn't start with a leading /
).
You can change it to this:
include_once 'headerSite.php';
That will look first in the same directory as the file that's including it (i.e. C:\xampp\htdocs\PoliticalForum\
in your example.