Running update-grup causes a lot of scary error messages being logged in dmesg because it fails to recognize the extended partition type (so it appears).
[ 1589.825598] Btrfs loaded
[ 1590.143489] EXT4-fs (sda2): unable to read superblock
[ 1590.147775] EXT4-fs (sda2): unable to read superblock
[ 1590.152399] EXT4-fs (sda2): unable to read superblock
[ 1590.158651] FAT-fs (sda2): invalid media value (0x60)
[ 1590.158661] FAT-fs (sda2): Can't find a valid FAT filesystem
[ 1590.196531] XFS (sda2): Invalid superblock magic number
[ 1590.206640] FAT-fs (sda2): invalid media value (0x60)
[ 1590.206652] FAT-fs (sda2): Can't find a valid FAT filesystem
[ 1590.220111] MINIX-fs: unable to read superblock
[ 1590.245014] attempt to access beyond end of device
[ 1590.245027] sda2: rw=16, want=3, limit=2
[ 1590.245033] hfsplus: unable to find HFS+ superblock
[ 1590.254463] qnx4: no qnx4 filesystem (no root dir).
[ 1590.257698] You didn't specify the type of your ufs filesystem
Disk /dev/sda: 233,8 GiB, 251059544064 bytes, 490350672 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0xce28d9ab
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 499711 497664 243M 83 Linux
/dev/sda2 501758 490348543 489846786 233,6G 5 Extended
/dev/sda5 501760 490348543 489846784 233,6G 8e Linux LVM
ProblemType: Bug
DistroRelease: Ubuntu 14.10
Package: grub-common 2.02~beta2-11
ProcVersionSignature: Ubuntu 3.16.0-17.23-generic 3.16.3
Uname: Linux 3.16.0-17-generic i686
NonfreeKernelModules: nvidia
ApportVersion: 2.14.7-0ubuntu2
Architecture: i386
CurrentDesktop: Unity
Date: Thu Sep 25 17:19:42 2014
InstallationDate: Installed on 2014-09-25 (0 days ago)
InstallationMedia: Ubuntu 14.10 "Utopic Unicorn" - Alpha i386 (20140923)
SourcePackage: grub2
UpgradeStatus: No upgrade log present (probably fresh install)
I am getting these message too. Are they benign?