This is on purpose. In the installer menu, you also show the use of "Detect and mount CD-ROM"; the elements of the installer menu are meant to be run somewhat in the same order as they appear, so on a standard install, the CD-ROM will be mounted before the preseed file is attempted to be read.
I've tested this on ubuntu-14.04.1-server-amd64.iso with no issues. Closing as "incomplete" for now, so please feel free to set it back to New if you have further details to contribute. ** Changed in: debian-installer (Ubuntu) Status: New => Incomplete ** Changed in: debian-installer (Ubuntu) Importance: Undecided => Low -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1396506 Title: Ubuntu Server installer does not mount /cdrom for preseeding To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/debian-installer/+bug/1396506/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs