Dear Maintainer,

update-grub spits the following lines for dmesg:

[236327.624046] EXT4-fs (sda2): unable to read superblock
[236327.625491] EXT4-fs (sda2): unable to read superblock
[236327.626887] EXT4-fs (sda2): unable to read superblock
[236327.628509] XFS (sda2): Invalid superblock magic number
[236327.661732] FAT-fs (sda2): utf8 is not a recommended IO charset for FAT filesystems, filesystem will be case sensitive!
[236327.661843] FAT-fs (sda2): bogus number of reserved sectors
[236327.661872] FAT-fs (sda2): Can't find a valid FAT filesystem
[236327.663306] FAT-fs (sda2): utf8 is not a recommended IO charset for FAT filesystems, filesystem will be case sensitive!
[236327.663413] FAT-fs (sda2): bogus number of reserved sectors
[236327.663441] FAT-fs (sda2): Can't find a valid FAT filesystem
[236327.665047] NTFS-fs error (device sda2): read_ntfs_boot_sector(): Primary boot sector is invalid.
[236327.665088] NTFS-fs error (device sda2): read_ntfs_boot_sector(): Mount option errors=recover not used. Aborting without trying to recover.
[236327.665138] NTFS-fs error (device sda2): ntfs_fill_super(): Not an NTFS volume.
[236327.666538] MINIX-fs: unable to read superblock
[236327.667914] attempt to access beyond end of device
[236327.667917] sda2: rw=16, want=3, limit=2
[236327.667919] hfsplus: unable to find HFS+ superblock
[236327.669394] qnx4: no qnx4 filesystem (no root dir).
[236327.670812] You didn't specify the type of your ufs filesystem

mount -t ufs -o ufstype=sun|sunx86|44bsd|ufs2|5xbsd|old|hp|nextstep|nextstep-cd|openstep ...
[236327.673497] hfs: can't find a HFS filesystem on dev sda2



/dev/sda2 is the root partition, I can boot normal and the partition is accessible.

I said /dev/sda2 is root partition, but it is not.
sda2 does not exist, it is sda1 for /boot and all other partitions are
in the extended partition.