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I decided to upgrade my windows 8 to windows 10. During the installation process, the computer rebooted and I got into the grub console, without having my usual menu.

I was able to proceed to the installation and use windows by choosing which hdd to boot on on my bios, but after the installation I can't boot into ubuntu again. Same issue with a grub shell.

On the grub shell, I tried to use ls (hdx,y)/ to display the information about the filesystems. Only one or two were readable, while the other always responded as unknown filesystem.

I booted on a boot-repair live disc, and was able to use the boot-repair tool, but it didn't fix anything and I still have the same issue.

Here is the boot info : http://paste.ubuntu.com/11969079/

What should I do to repair my grub install and be able to boot on linux?

EDIT: using fsck I got the following result :

lubuntu@lubuntu:~$ sudo e2fsck -C0 -p -f -v /dev/sdb6
e2fsck: Bad magic number in super-block while trying to open /dev/sdb6
/dev/sdb6: 
The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem.  If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
    e2fsck -b 8193 <device>
 or
    e2fsck -b 32768 <device>

lubuntu@lubuntu:~$

I believe /dev/sdb6 was the partition where my system was installed while /dev/sdb2 was where I had my /boot.

I'm unable to mount /dev/sdb6 on a linux livecd.

MagicMicky
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  • Was your install in sdb6, or the partition that Boot-Repair is showing that it cannot mount or unknown filetype? You may want to run fsck on that partition. http://askubuntu.com/questions/642504/ubuntu-14-04-is-not-booting-normaly-after-a-manual-hard-boot/642789#642789 – oldfred Jul 30 '15 at 20:44
  • @oldfred I belive that my boot partition was sdb3 and my system was sdb6. Will try fsck. – MagicMicky Jul 30 '15 at 22:16
  • the sdb3 is the Microsoft reserved partition and must be kept for Windows. It is unformatted, so various Linux tools may complain since it is unformatted. – oldfred Jul 30 '15 at 23:46
  • @oldfred. Oh true! I meant sdb2 for the boot partition – MagicMicky Jul 31 '15 at 06:46
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    Your sdb2 is the ESP - efi system partition which is not normally the Ubuntu /boot partition. In fstab you will see the ESP mounted as /boot/efi. It has grub efi boot files only. If you have a separate /boot partition it is mounted at /boot. And that whether partition or folder in / (root) has the rest of grub & the kernels. Normally desktop installs do not need separate /boot partition, but if full drive encryption which uses LVM, you will have a /boot partition. – oldfred Jul 31 '15 at 15:05

2 Answers2

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I did it by run live-cd with Ubuntu (can be any other distro) and install boot-repair. Everything is written here: https://help.ubuntu.com/community/Boot-Repair

Run in live-cd terminal

sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install -y boot-repair && boot-repair

Then just click Recommended Repair. This works, i have used it a few times.

iacobus
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The options are: 1. CMOS. HDD2 can be replaced first, it is different. 2. LIVE CD and reinstall GRUB on the first partition.It is not always possible. 3. Do an external drive system. 16 MB is enough. Basic ubuntu and suggested programs: Synaptic - installs GRUB and useful package manager. Gparted knows everything about the partitions and do everything. This is dangerous, do not make mistakes. Midnight Commander is also operating console over-File's control. With these you can improve many mistakes. Space shall be that the programs work.

Istvan Bela Turk
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