/boot partition is 100% full
Identify what kernel you are running
cd /boot
uname -a
du -sk * | sort -n
Remove unused version
sudo rm -rf initrd.img-3.xx.x-xx-generic
sudo rm -rf vmlinuz-3.19.0-25-generic
df -hT
Now that we have some space on /boot let’s do some clean up
sudo apt-get remove linux-headers-x.x.xx-xx
sudo apt-get -f install
sudo apt-get install autoremove
Now that space problem is resolved, let’s do some upgrade
sudo apt-get upgrade
sudo apt-get dist-upgrade
There is no public key available for the following key IDs:
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys xxxxxxxxxxx