It is a server setup issue. Basically in Apache you have a config directive like:

    ScriptAlias /cgi-bin/ "/home/some.site.com/cgi-bin/"


    <Directory "/home/some.site.com/cgi-bin">
        AllowOverride None
        Options None
        Order allow,deny
        Allow from all
    </Directory>
[download]

This lets Apache know that the URL path /cgi-bin means look at /home/some.site.com/cgi-bin and exec the scripts in there.

HTTPS basically has its own set of config directives that are more or less independent of the HTTP ones. There are several ways it gets set up but evidently your HTTPS config does not map to a cgi-bin dir OR it maps to a different directory. The net result is that Apache can't find your script.