Routine system update failed (Ubuntu 22.04.4 LTS)

[Bo Berglund]

Based on a discussion post here by Ian Burntlett some time ago I have compiled a
script to do system updates which looks like this:

-----------
#!/bin/bash
if [ "$1" != "Y" ]; then
  echo "Error! Call syntax: sudo $0 Y"
  echo "Try again!"
  exit -1
fi

set -e # exit immediately if a command returns a non-zero status
set -x # print a trace of simple commands

apt update # download package information
apt full-upgrade -y # upgrade and remove packages if required
apt autoremove -y
apt autoclean # removes virtually useless files from the cache
#apt purge # even more tidying up

echo "Update completed!"
exit 0
-----------

Today I ran the script on an Ubuntu system showing this on the login screen:
Ubuntu 22.04.4 LTS (GNU/Linux 5.15.0-117-generic x86_64)

But instead of ending amicably as it has in the past it showed this towards the
end:


Updating /boot/grub/menu.lst ... done

/etc/kernel/postinst.d/zz-update-grub:
Sourcing file `/etc/default/grub'
Sourcing file `/etc/default/grub.d/init-select.cfg'
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-5.15.0-122-generic
Found initrd image: /boot/initrd.img-5.15.0-122-generic
Found linux image: /boot/vmlinuz-5.15.0-117-generic
Found initrd image: /boot/initrd.img-5.15.0-117-generic
Found linux image: /boot/vmlinuz-5.15.0-107-generic
Found initrd image: /boot/initrd.img-5.15.0-107-generic
Warning: os-prober will not be executed to detect other bootable partitions.
Systems on them will not be added to the GRUB boot configuration.
Check GRUB_DISABLE_OS_PROBER documentation entry.
done
Processing triggers for initramfs-tools (0.140ubuntu13.4) ...
update-initramfs: Generating /boot/initrd.img-5.15.0-122-generic
zstd: error 25 : Write error : No space left on device (cannot write compressed
block)
E: mkinitramfs failure zstd -q -1 -T0 25  <== ERROR here!
update-initramfs: failed for /boot/initrd.img-5.15.0-122-generic with 1.
dpkg: error processing package initramfs-tools (--configure):
 installed initramfs-tools package post-installation script subprocess returned
error exit status 1
Errors were encountered while processing:
 initramfs-tools
needrestart is being skipped since dpkg has failed
E: Sub-process /usr/bin/dpkg returned an error code (1)

So I checked the drive situation:

~$ df -h
Filesystem                         Size  Used Avail Use% Mounted on
tmpfs                               96M  1.4M   95M   2% /run
/dev/mapper/agivpnserver--vg-root   28G   19G  7.5G  72% /
tmpfs                              479M     0  479M   0% /dev/shm
tmpfs                              5.0M     0  5.0M   0% /run/lock
/dev/sda1                          470M  394M   52M  89% /boot
tmpfs                               96M   32K   96M   1% /run/user/1000

I cannot see where the disk space problem is located...
There is 11% left on /boot, is that the problem and if so what to do about it?

Any advice greatly appreciated!

-- 
Bo Berglund
Developer in Sweden