If the /boot partition fills to 100% you’ll likely find yourself stuck in a loop. In order to remove old Linux kernels and free space you will likely first need to install dependencies, but to install those dependencies you require free space in the /boot partition. To break out of this bad recursion joke, old kernels will need to be forcefully removed.
Everything here will require root permissions. Either launch a root shell now or prepend sudo to each command
sudo -i
First up, let’s see which kernel is running
uname -r
Take note of this. Do not delete it this kernel.
List installed kernels
dpkg -l | grep linux-image
Delete kernels in bulk, using the minor version number to differentiate between them and save some time. I like to leave ~3 kernels in place in case of emergency
rm -rf /boot/*-4.4.0-{31,34,36,38,42,45,47,51,53,57,59}-*
Resolve dependency issues
apt-get -f install
Clean up old kernel residue
apt-get autoremove
Update grub to reflect the change in available kernels
update-grub
Reboot and continue what you were trying to do
reboot