Comment 3 for bug 1059231

I can confirm this bug for Kubuntu. Like the bug reporter the upgrade was performed without any errors or warnings shown. After reboot, a grub rescue prompt was shown:

error: file not found.
grub rescue> _

Luckily, I already have a usb rescue disc handy. A simple grub-install command solves the error. All my grub menu entries are restored and the system boots properly again.
I have experienced this error at least the last 4 times I upgraded my kubuntu installation. I upgraded 2 weeks ago from oneiric to precise, and last week from precise to quantal.

Harddisk configuration
/dev/sda is a Maxtor drive on an addon pci card using a silicon image 3531 serial ata controller
/dev/sdb is a Samsung drive on an onboard Nvidia mcp51 serial ata controller

output of df
$ df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdb9 19198676 17279464 943956 95% /
udev 1528136 4 1528132 1% /dev
tmpfs 616484 908 615576 1% /run
none 5120 0 5120 0% /run/lock
none 1541204 80 1541124 1% /run/shm
none 102400 0 102400 0% /run/user
/dev/sda3 243056000 220903612 22152388 91% /home
/dev/sdb8 960504 88060 823652 10% /boot
/dev/sdb5 10231392 6068784 4162608 60% /media/personal

Now that I look at this it strikes me as strange that my root and boot dirs are on /dev/sdb, which is on the motherboard sata controller. Could it be that the ubuntu-release-upgrader installs grub on the wrong drive?

output of some more stuff
/dev/disk/by-path$ ll
total 0
lrwxrwxrwx 1 root root 9 nov 15 17:17 pci-0000:00:0e.0-scsi-0:0:0:0 -> ../../sdb
lrwxrwxrwx 1 root root 10 nov 15 17:17 pci-0000:00:0e.0-scsi-0:0:0:0-part1 -> ../../sdb1
lrwxrwxrwx 1 root root 10 nov 15 17:17 pci-0000:00:0e.0-scsi-0:0:0:0-part2 -> ../../sdb2
lrwxrwxrwx 1 root root 10 nov 15 17:17 pci-0000:00:0e.0-scsi-0:0:0:0-part3 -> ../../sdb3
lrwxrwxrwx 1 root root 10 nov 15 17:17 pci-0000:00:0e.0-scsi-0:0:0:0-part5 -> ../../sdb5
lrwxrwxrwx 1 root root 10 nov 15 17:17 pci-0000:00:0e.0-scsi-0:0:0:0-part6 -> ../../sdb6
lrwxrwxrwx 1 root root 10 nov 15 17:17 pci-0000:00:0e.0-scsi-0:0:0:0-part7 -> ../../sdb7
lrwxrwxrwx 1 root root 10 nov 15 17:17 pci-0000:00:0e.0-scsi-0:0:0:0-part8 -> ../../sdb8
lrwxrwxrwx 1 root root 10 nov 15 17:17 pci-0000:00:0e.0-scsi-0:0:0:0-part9 -> ../../sdb9
lrwxrwxrwx 1 root root 9 nov 15 17:17 pci-0000:01:00.0-scsi-0:0:0:0 -> ../../sda
lrwxrwxrwx 1 root root 10 nov 15 17:17 pci-0000:01:00.0-scsi-0:0:0:0-part1 -> ../../sda1
lrwxrwxrwx 1 root root 10 nov 15 17:17 pci-0000:01:00.0-scsi-0:0:0:0-part3 -> ../../sda3

$ lspci
<snip>
00:0e.0 IDE interface: NVIDIA Corporation MCP51 Serial ATA Controller (rev a1)
00:0f.0 IDE interface: NVIDIA Corporation MCP51 Serial ATA Controller (rev a1)
<snip>
01:00.0 Mass storage controller: Silicon Image, Inc. SiI 3531 [SATALink/SATARaid] Serial ATA Controller (rev 01)
<snip>

I added the files present in /var/log/dist-upgrade from the last upgrade as requested by https://wiki.ubuntu.com/DebuggingUpdateManager.