Stuck at grub rescue after upgrade

[RobH]

I upgraded my ubuntu 18,04 system to 20.04 and selected the wrong drive
to install grub , during the process...doh!
The reason why was because when it came to installing grub, 2 drives
were listed, 1 being an ssd. Now I only have one spinning disk drive ,
so I selected the other.On reboot I get the grub rescue prompt.

I have tried fixing grub with this:
ls (hd0,msdos1)
(hd0,msdos1): file system is ext2
set boot=(hd0,msdos1)
set prefix=(hd0.msdos1)/boot/grub
insmod normal
returns:
error: symbol 'grub_file_filters' not found.

I have a 20.4 live usb, and tried:
sudo fdisk-l
sudo grub-install /dev/sda1
which returned:
grub-install; error: failed to get canonical path of '/cow'.

Is there any other way of fixing my mistake!!

Thanks

[Jonathan N. Little]

Post by RobH
sudo grub-install /dev/sda1

You normally shouldn't be installing grub on the partition but to the mbr


Live Session:

sudo mount /dev/sda1 /mnt

sudo grub-install --boot-directory=/mnt/boot /dev/sda
|
# note: no partition number-------------------------+

[RobH]

Post by Jonathan N. Little

Post by RobH
sudo grub-install /dev/sda1

You normally shouldn't be installing grub on the partition but to the mbr
sudo mount /dev/sda1 /mnt
sudo grub-install --boot-directory=/mnt/boot /dev/sda
|
# note: no partition number-------------------------+

Thanks Jamie, you came to the rescue again!!
Yes, that has got me back in to my 20.04 system now.

[Johnny]

On Sun, 29 Nov 2020 07:34:48 -0500

Post by Jonathan N. Little

Post by RobH
sudo grub-install /dev/sda1

You normally shouldn't be installing grub on the partition but to the mbr
sudo mount /dev/sda1 /mnt
sudo grub-install --boot-directory=/mnt/boot /dev/sda
|
# note: no partition number-------------------------+

Grub Rescue Commands to Fix Boot Issues
https://linoxide.com/linux-how-to/grub-rescue-commands/

I think the grub rescue screen is worthless, I have never been able to
accomplish anything with it.

After reading this article, and looking at the commands you have to
enter, it's a lot simpler to do what you said.

When the grub rescue screen comes up it should say exactly what you
said.

[RobH]

Post by Johnny
On Sun, 29 Nov 2020 07:34:48 -0500

Post by Jonathan N. Little

Post by RobH
sudo grub-install /dev/sda1

You normally shouldn't be installing grub on the partition but to the mbr
sudo mount /dev/sda1 /mnt
sudo grub-install --boot-directory=/mnt/boot /dev/sda
|
# note: no partition number-------------------------+

Grub Rescue Commands to Fix Boot Issues
https://linoxide.com/linux-how-to/grub-rescue-commands/
I think the grub rescue screen is worthless, I have never been able to
accomplish anything with it.
After reading this article, and looking at the commands you have to
enter, it's a lot simpler to do what you said.
When the grub rescue screen comes up it should say exactly what you
said.

I had some problems with some of those commands on that page:

This one :
linux (hd0,msdos1)/vmlinuz-3.10.0-1127.13.1.el7.x86_64 root=/dev/sda1
'linux' not recognised, or similar.

Then this:
grub > insmod normal
returns:
error: symbol 'grub_file_filters' not found.


Jamies' method was much easier,

[Jonathan N. Little]

Post by RobH
Jamies' method was much easier,

Who's Jamie?

[RobH]

Post by Jonathan N. Little

Post by RobH
Jamies' method was much easier,

Who's Jamie?

Oops sorry, Jonathan