Grub corrupted on shutdown

[dantes33]

Ubuntu 20.04 crashed badly and then grub booted on a minimal text interface. I likely can boot Windows partition changing the bios startup sequence (yes, I've two disks for any OS) but I can't get Ubuntu partition back. It happened as I was cleaning the system with Bleachbit (never more!) … maybe a screen saver while cleaner processing caused the system freeze in the wrong moment.
Using a live usb I made a file system check on every partition (sdb1 and sdb5) and got an undamaged system partitions feedback message.
I also run Grub Repair tool but I had things getting worst, because I had two error message: the first is about partition mapper/vgubuntu-root (Ubuntu 20.04.2 LTS) quite full, but there’s no way to solve the issue deleting files for having more space (I always get recursive message about “at least 128 Mega needed”, and seemed to me that such location is aleatory), so I ignored it, went to the next step and got second error message:

“Please enable a repository containing the [grub-efi-amd64-signed] packages in the software sources of Ubuntu 20.04.2 LTS (mapper/vgubuntu-root)”

I found a patch to this issue (never been able to google it again on further attempts, so I can't link it just now) and to go ahead until the “Boot successfully repaired” message.

But since I write here down the subsequent link generated by Grub Repair :

http://paste.ubuntu.com/p/pvQCYbjdXw/

it has not been that successful!

I also tried with Grub Customizer but I have the message

“grub-mkconfig wrong execution
/usr/sbin/grub-probe:error:failed to get canonical path of /-cow”

https://askubuntu.com/questions/2544...al-path-of-cow

I chased this “cow” around its path for a couple of hours also trying to setting up a chroot environment

https://unix.stackexchange.com/quest...al-path-of-cow

but no way.

I also post here some mount attempts over sdb partition the SSD Ubuntu is installed on

ubuntu@ubuntu:~$ sudo mount /dev/sdb1 /mnt

mount: /mnt: /dev/sdb1 already mounted on /mnt.
ubuntu@ubuntu:~$ sudo mount /dev/sdb1 /mnt/boot/efi
mount: /mnt/boot/efi: mount point does not exist.
ubuntu@ubuntu:~$ sudo mount /dev/sdb1 /mnt/efi
ubuntu@ubuntu:~$ for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done
mount: /mnt/dev: mount point does not exist.
mount: /mnt/dev/pts: mount point does not exist.
mount: /mnt/proc: mount point does not exist.
mount: /mnt/sys: mount point does not exist.
mount: /mnt/run: mount point does not exist.
ubuntu@ubuntu:~$ sudo mount /dev/sdb5 /mnt
mount: /mnt: unknown filesystem type 'LVM2_member'.

Thanks in advance for any help (my Ubuntu optimized installation, the upgrades, add-ons, selected software is still there)

[tea for one]

Zero replies after one day does not bode well.

A system freeze/crash while using bleachbit is undoubtedly impossible to diagnose because there are too many files in an unknown variable state
On top of that, add in LVM and I would doubt if any user has experience of this combination.

Include me in the above.

Nevertheless, onwards and upwards.

Boot repair line 170 – 1 OS detected Windows 8 or 10 on sda5
It would be impossible for boot-repair to re-install grub to an undetected Ubuntu OS

However, you mentioned that sdb1 to sdb5 are undamaged.
The file system may be OK but there still could be missing files which prevent booting.

Do you have back-ups of both your Windows data and Ubuntu data?
If not, please create back-ups.

I imagine that trying to boot from UEFI one-time boot menu does not work due to missing grub?

It appears that you tried to add grub via a live session but I think that you did not run the commands correctly:-

According to boot-repair lines 349 -353
sdb5 is your Ubuntu system partition
sdb1 is your Ubuntu EFI partition
sdb is your Ubuntu disk

Perhaps, try again in a live session:-

sudo mount /dev/sdb5 /mnt
sudo mount /dev/sdb1 /mnt/boot/efi
for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done
sudo chroot /mnt
grub-install /dev/sdb
update-grub

It may work, it may not – fingers crossed.

[dantes33]

This is what I got by placing the suggested commands; suddenly the first one returns no mount point for lvm partition

sudo mount /dev/sdb5 /mnt
mount: /mnt: unknown filesystem type 'LVM2_member'.

seems that lvm does not follow the traditional mount rules (of e.g. fat 32 or ext4). I do not know if it makes sense but gparted describes lvm partition as "activated - deactivated" instead of mounted ... maybe the "mount" command shold be replaced with another one? Anyway I was able to "activate" the partition via gparted (by the way, what is LVM2_"member"?).

So I went to subsequent command, attempting to mount the boot F32 partition efi, (sdb1) I have the result:

sudo mount /dev/sdb1 /mnt/boot/efi
mount: /mnt/boot/efi: mount point does not exist.

Only if I omit the boot/efi parameters I can mount sdb1 partition

sudo mount /dev/sdb1 /mnt/
ubuntu@ubuntu:~$

moving on the sequent command

for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done

I have:

mount: /mnt/dev: mount point does not exist.
mount: /mnt/dev/pts: mount point does not exist.
mount: /mnt/proc: mount point does not exist.
mount: /mnt/sys: mount point does not exist.
mount: /mnt/run: mount point does not exist.

then,

sudo chroot /mnt

gives back:

chroot: failed to run command ‘/bin/bash’: No such file or directory

and

grub-install /dev/sdb

gives:

installazione per la piattaforma x86_64-efi.
grub-install: errore: impossibile trovare la directory EFI.

(I guess italian here is quite understandeable, anyway: "install for x86_64-efi board / grub-install: error: impossible to find the directory EFI.")

finally with:

sudo update-grub

the result is:

/usr/sbin/grub-probe: errore: recupero del percorso canonico di "/cow" non riuscito

(I am back to the canonical path for "/cow" error)

All these command have been placed running a live.
I can add that I had two crashes, from the first one I still was able to launch ubuntu with grub option for recovery mode. But then I made an attempt with Grub Repair and I had a worst result: the bootloader was quite wiped down to the minimal grub command line from which I'm only able to reboot

Seems the repair attempts do not find efi partition and I suspect it is only on sda disk, which hosts windows OS, the one I'd prefer to do not touch in any way (during the many attempts after a reboot I also got a Windows Restore screen alert).

Surely I need more finger to cross

[Dennis N]

A small bit of help:

Your Ubuntu is an LVM installation.

You can't mount a disk partition that's used for LVM (like sdb5). There is no traditional file system. Instead, if you want to mount Ubuntu's root file system, you mount the logical volume it's installed on:

sudo mount /dev/vgubuntu/root /mnt/tmp

would mount Ubuntu's root file system at /mnt/tmp (if that directory has been created).

Then you can do whatever chroot procedures you have in mind.

[dantes33]

I went very close now ... at first the command Dennis give to me won't work but in some way I could mount combining Denni's instructions with mount instances of "Disk" application in Ubuntu (do not ask the sequence ...) seems me to remember I first mounted the sdb partitions using "Disk" GUI and THEN the above command get working. So I had the Zero's commands working ... except the last one (grub-install) because a phantom "lupin-support" is missing and can't be installed

ubuntu@ubuntu:~$ sudo mount /dev/sdb1 /mnt/boot/efi
ubuntu@ubuntu:~$
ubuntu@ubuntu:~$ for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done
ubuntu@ubuntu:~$ sudo chroot /mnt
root@ubuntu:/#
root@ubuntu:/# grub-install /dev/sdb

Command «grub-install» not found but can be installed with:

apt install lupin-support # version 0.57build1, or
apt install grub2-common # version 2.04-1ubuntu26.11

root@ubuntu:/# apt install lupin-support
Reading dependencies tree ... done
Generating dependencies tree ... done
Reading status information ... done
E: Impossible to find packet lupin-support

the same for grub-install command (grub-common required but can't install)

root@ubuntu:/# apt install grub2-common
Reading dependencies tree ... done
Generating dependencies tree ... done
Reading status information ... done
E: Impossible to find packet grub2-common

less finger to cross, ... some other help needed, though

[dantes33]

I append a screen shoot of my system disks running on a Ubuntu live (another usb key for data is mounted too).

So, the command

sudo mount /dev/vgubuntu/root /mnt/tmp

won't work anymore and gives back

mount: /mnt/tmp: mount point does not exist.

The command sequence spotted above by Zero cannot be performed.
The sdb5 partition formatted with lvm format cannot be mounted also if "Disk" and "Gparted" seemed able to mount / activate it. I can't fix anyway the root partition.
So I think I'm going to install a new instance of Ubuntu over the former. I read somewhere that if one keeps t he /home partition his data are served, but I'm not sure how to do that considering the 'damned' lvm format levels out everything.
I'll keep attempting some solution for few day then I restart with a new installation, hoping to do not miss other OS.
Any idea?

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