You're getting fixated on the filename. The problem is 'Permission Denied'.
That code says:
- Is there a FREEPBX_CONF environment variable? If so, try to load that file.
- If not, try to load /etc/freepbx.conf
- If that fails, try to load /etc/asterisk/freepbx.conf
That last one shouldn't be there, and I wanted to remove it for 13, but we never got around to it. It'll probably go in 14, it's a legacy configuration file that isn't used any more.
However. Permission Denied. That's your problem. Really, it is. Your machine has something severely wrong with it.
If you try to load a file that doesn't exist, it should say 'No such File or Directory'. Try it yourself:
error_reporting(E_ALL);
<?php
include("/non/existing/file");