6

After Upgrading from 18.04 to 20.04 I've notices several warnings during shutdown or reboot like:

Failed to unmount /oldroot: Device or Resource busy
Failed to unmount /oldroot/dev/pts: Device or Resource busy
Failed to unmount /oldroot/dev: Device or Resource busy
Failed to unmount /oldroot/sys: Device or Resource busy

Sometimes it's visible on the screen, sometimes it's covered by the splash.
I cannot find anything related using journalctl or logs, the only thing I've found is:

abr 23 22:24:36 vanburen07-G5-5590 sudo[6451]: vanburen07 : TTY=pts/0 ; PWD=/home/vanburen07 ; USER=root ; COMMAND=/bin/umount /oldroot/dev/pts

There's nothing specific in fstab:

 <file system> <mount point>   <type>  <options>       <dump>  <pass>
# / was on /dev/nvme0n1p3 during installation
UUID=063c6892-66d6-4598-9dcf-82136ad4ea81 /               ext4    errors=remount-ro 0       1
# /boot/efi was on /dev/nvme0n1p1 during installation
UUID=C000-EAB9  /boot/efi       vfat    umask=0077      0       1
/swapfile                                 none            swap    sw              0       0

The only thing I was able to find were on Arch/Manajaro forums and the suggested workaround is to modify a file that doesn't esxist in Ubuntu: /etc/mkinitcpio.conf

I don't think this is a huge issue as it doesn't cause visible crush or even error in syslogs but yet it'd be nice to know the reason.

4
  • I'm also experiencing this on Kubuntu 20.04...but it wasn't an upgrade, it was a fresh install. I've tried multiple kernel versions but it makes no difference - the latest 5.4, as well as the latest 5.6.
    – Metal450
    May 27, 2020 at 7:36
  • not exactly sure why but it has gone after reinstalling it formating the disk. that can be the difference May 27, 2020 at 16:36
  • Have you posted a bug report on the launchpad? I have the same issue, and I always install fresh with formatting of partitions. Launchpad is the place for bug reports... not here. ;-) Indeed, same as you, it seems to have no effect at all but spit a few lines on the screen on shutdown, so probably not a dramatic bug!
    – Zakhar
    Jun 25, 2020 at 16:18
  • No I haven't, since the issue is gone and I haven't recieved a lot of feedback here I considered it not essencial and rather related to my system/upgrade. Jun 26, 2020 at 20:22

3 Answers 3

3

Hope this will help. I think it is because of the unused kernel because I have upgraded my ubuntu from 18.04 LTS to 20.04 LTS and in few days after that I encountered the problem during shutdown and restart.

Just remove all unused kernels without doing clean re installation of the system, just visit this link on removing unused kernels --> https://www.cyberciti.biz/faq/ubuntu-18-04-remove-all-unused-old-kernels/

God Bless everyone.

1

This happened to me too after switching motherboards. It turns out that a MBR compatibility setting was hidden inside the Windows submenu (that I skipped initially) which seems to cause this.

After changing these settings, the error disappeared:

  • BIOS>Settings>Boot>Boot Mode Select [LEGACY+UEFI] set to UEFI
  • BIOS>Settings>Advanced>Windows OS Configuration>BIOS UEFI/CSM Mode set to UEFI
2
  • it's happening mostly those laptop, which has Intel C-State error. Dec 13, 2020 at 7:03
  • Solved via the hint, thanks! Sep 13, 2021 at 21:32
0

Seems to be related to update from 18.04, for some reason it left some old legacty Kernels untouched. Reinstalling system (because of another issue) solved the problem.

1
  • 1
    Sorry Ivan, your statement is not true, as I have a brand new laptop on 20.04 LTS, installed from scratch. and I experience the same issue.
    – Chris
    Jul 9, 2021 at 9:14

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.