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Fixing "groot must be grub root device" on ibmcloud

nibalizer profile image Spencer Krum ・2 min read

Some images on ibmcloud have an issue when installing new kernels (and thus rebuilding the initramfs and grub config files).

# apt-get upgrade
...
Processing triggers for initramfs-tools (0.130ubuntu3.9) ...
update-initramfs: Generating /boot/initrd.img-4.15.0-42-generic
I: The initramfs will attempt to resume from /dev/vdc
I: (UUID=083a8bfd-95a8-4808-bd75-ed3c1be04dd4)
I: Set the RESUME variable to override this.
Setting up ubuntu-server (1.417.4) ...
Processing triggers for linux-image-4.15.0-99-generic (4.15.0-99.100) ...
/etc/kernel/postinst.d/initramfs-tools:
update-initramfs: Generating /boot/initrd.img-4.15.0-99-generic
I: The initramfs will attempt to resume from /dev/vdc
I: (UUID=083a8bfd-95a8-4808-bd75-ed3c1be04dd4)
I: Set the RESUME variable to override this.
/etc/kernel/postinst.d/x-grub-legacy-ec2:
Searching for GRUB installation directory ... found: /boot/grub
Searching for default file ... found: /boot/grub/default
Testing for an existing GRUB menu.lst file ... found: /boot/grub/menu.lst
uuid not supported. update 'groot' in /boot/grub/menu.lst

groot must be grub root device (ie '(hd0)'). not 'LABEL=cloudimg-rootfs'

run-parts: /etc/kernel/postinst.d/x-grub-legacy-ec2 exited with return code 1
dpkg: error processing package linux-image-4.15.0-99-generic (--configure):
 installed linux-image-4.15.0-99-generic package post-installation script subprocess returned error exit status 1
Processing triggers for ureadahead (0.100.0-21) ...
Errors were encountered while processing:
 linux-image-4.15.0-99-generic
E: Sub-process /usr/bin/dpkg returned an error code (1)

Ooof. Very annoying.

Until we get a fix everywhere, you can fix this very easily yourself.

Edit: /boot/grub/menu.lst

Find this section:

...
## default grub root device
## e.g. groot=LABEL=cloudimg-rootfs
# groot=LABEL=cloudimg-rootfs

...

Change # groot=LABEL=cloudimg-rootfs to # groot=(hd0) (leaving the comment)

Then have the package manager try again

# apt-get install -f

This should succeed without issue. Then you can reboot to test the change

# reboot

Posted on by:

nibalizer profile

Spencer Krum

@nibalizer

I fling root shells, write bad programs, deploy containers, and watch esports

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