Estada.ch   _{Rust Engineering, Event-management, and Distributed Systems}

Identify that you have this problem checklist

This is very important: Applying this fix is a wast of your time if that is not your problem.

• df -h /boot shows 100% usage
• apt upgrade or apt dist-upgrade or apt-get upgrade or dpkg --configure -a are complaining about the package linux
• You have a terminal to the system open (called Terminal A)
• You have a second terminal to the system open (called Terminal B)

Become root with sudo (Terminal A & B)

If you are not logged in as root via ssh already:

sudo -i

Do this in both terminals.

Empty the existing images (Terminal A)

First, decide which kernels are no longer needed:

cd /boot
ls -hasl

Second, assuming we have multiple versions of the 4.15.0 kernel, for example (160, 163, 166, 167, 169)

• Get the current kernel to keep: uname -r
  • the current version is something like 5.4.0
• Empty the old initramfs in a loop watch "df -h . ; echo | tee initrd.img-4.15.0-16*" because apt on Ubuntu recreates these files during the update process all the time (yes even when you remove a kernel)

Remove old kernels (Terminal B)

The simplest way is to have apt remove old versions for us:

• Now there must be some space left again, check with df -h /boot
• Remove the old versions with sudo apt autoremove

Now apt can remove all unused kernels not just the 4.15.0-* ones.

Cleanup old empty files (Terminal A)

• Stop the watch process with Ctrl + C
• Find the file with size 1 with ls -hasl /boot (should be just one, could be more)
• Remove the old image file with a command like this rm /boot/initrd-4.15.0-167-generic

Cleanup & Future

Leave the root shells with exit or Ctrl + D and enjoy that you fixed a system.

Consider this command for updating your system in the future and avoid having this problem again:

df -h && apt update && apt dist-upgrade && apt autoremove