I have also experienced this problem (as Stan has described) but with a fresh install of Dapper alt install. Everything works according to plan (and according to the wiki entry) but then I fall into the same pit: "It kept telling me the filesystem didn't exist until I tried "mount -t ext3 /dev/mapper/VolGroup00-LogVol03 /mnt/ubuntu" and it mounted. So it isn't detecting the filesystem type, needs to be told what it is, and is giving a misleading message that the root filesystem simply doesn't exist."
-- root on lvm fails to boot. https://launchpad.net/bugs/29858 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
