An Apache VHOST was moved to a different host from the Production Web server. VHOSTs with SSL (https:) support require their individual IP addresses, and shouldn't be configured as named-vhosts (sharing another VHOSTs IP address). When the VHOST was moved to the target Web server, the VHOST configuration had to be changed from named to IP based VHOST. This was an oversight by Systems Administration. The problem has since been fixed.