Problem to boot the VM machine after upgrading from Ubuntu 18.04.3 to 20.04

Question

Problem to boot the VM machine after upgrading from Ubuntu 18.04.3 to 20.04

Hung Duong 5

I have a problem booting the VM machine after upgrading OS to Ubuntu 20.04. I got an error in boot diagnostics:

error: symbol 'grub_file_filter' not found.

Entering rescue mode...

grub rescue>

I do not have a backup. How could I fix this issue?

vipullag-MSFT 26,487 Reputation points Moderator

2023-07-20T12:38:30.3833333+00:00

Hello Hung Duong

Any update on the issue?

Just checking in to see if you got a chance to see previous response.

If the suggested response helped you resolve your issue, please 'Accept as answer', so that it can help others in the community looking for help on similar topics.
David Moen - Computer Professionals 0 Reputation points

2023-09-04T16:03:39.7933333+00:00

Hi there, I'm having this exact issue with an Ubuntu VM not booting after upgrading it. The boot diagnostic screen displays the error

error: symbol 'grub_file_filter' not found.

Entering rescue mode...

grub rescue>

But when I enter the serial console, a blinking cursor is displayed, not the grub rescue command. I did find an article that indicated that I should hold the escape key down while rebooting the VM, but that didn't seem to change anything. How can I get to the grub rescue prompt in the serial terminal to try the steps you have indicated for recovery?
Hung Duong 5 Reputation points

2023-09-11T04:14:00.9533333+00:00

Hi @David Moen - Computer Professionals,

Please follow this documents to rescue. I got success after follow it.

https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/chroot-environment-linux#ubuntu-16x--ubuntu-18x--ubuntu-2004

1 answer

Your answer

vipullag-MSFT 26,487 Reputation points Moderator

2023-07-20T12:38:30.3833333+00:00

Hello Hung Duong

Any update on the issue?

Just checking in to see if you got a chance to see previous response.

If the suggested response helped you resolve your issue, please 'Accept as answer', so that it can help others in the community looking for help on similar topics.
David Moen - Computer Professionals 0 Reputation points

2023-09-04T16:03:39.7933333+00:00

Hi there, I'm having this exact issue with an Ubuntu VM not booting after upgrading it. The boot diagnostic screen displays the error

error: symbol 'grub_file_filter' not found.

Entering rescue mode...

grub rescue>

But when I enter the serial console, a blinking cursor is displayed, not the grub rescue command. I did find an article that indicated that I should hold the escape key down while rebooting the VM, but that didn't seem to change anything. How can I get to the grub rescue prompt in the serial terminal to try the steps you have indicated for recovery?
Hung Duong 5 Reputation points

2023-09-11T04:14:00.9533333+00:00

Hi @David Moen - Computer Professionals,

Please follow this documents to rescue. I got success after follow it.

https://learn.microsoft.com/en-us/troubleshoot/azure/virtual-machines/chroot-environment-linux#ubuntu-16x--ubuntu-18x--ubuntu-2004

Answer 1

Hello Hung Duong

Welcome to Microsoft Q&A Platform, thanks for posting your query here.

It looks like the error message you're seeing is related to the GRUB bootloader. This error can occur if the GRUB configuration is not updated correctly during the upgrade process.

To fix this issue, you can try the following steps:

Check the GRUB configuration file, boot into the rescue mode and use the following commands:

grub rescue> set root=(hd0,1)

grub rescue> configfile /boot/grub/grub.cfg

If this resolves the issue and allows you to boot into Ubuntu, you can update the GRUB configuration file permanently using the following command:

sudo update-grub

Restart the VM to check if it boots normally.

If the above step did not resolve the problem, you can try reinstalling GRUB.

1.Boot the VM from an Ubuntu 20.04 installation ISO. You can attach the ISO to the VM in the Azure portal.

2.Once the VM is booted from the ISO, open a terminal and run the following command to identify the partition where Ubuntu is installed:

sudo fdisk -l

3.Look for the partition that contains the Ubuntu installation. It should be labeled as "Linux" in the "System" column.

4.Mount the partition by running the following command, replacing /dev/sda1 with the partition you identified in step 3:

sudo mount /dev/sda1 /mnt

5.Chroot into the mounted partition by running the following command:

sudo chroot /mnt

6.Reinstall the GRUB bootloader by running the following command:

sudo grub-install /dev/sda

7.Update the GRUB configuration by running the following command:

sudo update-grub

8.Exit the chroot environment by running the following command:

exit

9.Unmount the partition by running the following command:

sudo umount /mnt

10.Reboot the VM and see if it boots up correctly.

If these steps don't work, I would recommend to seek additional help from the Ubuntu community here(https://ubuntuforums.org/).

Hope this helps.

David Moen - Computer Professionals 0 Reputation points

2023-09-04T16:07:06.9633333+00:00

I am facing the same issue, the boot diagnostics report shows a screen shot with the same error message as the original poster, but when I open a serial console window, the grub rescue prompt is not displayed, just a blinking cursor. The text at the top of the box gives the instruction to hit the "Enter" key to display a login prompt, but that doesn't do anything. How can I get to the grub rescue command?

Share via

Problem to boot the VM machine after upgrading from Ubuntu 18.04.3 to 20.04

1 answer

Your answer