Linux/boot cleanup

As the upgrade/boot partition becomes more and more full, the reason for subsequent inability to upgrade is because each upgrade may upgrade the kernel but the old kernel is not deleted, which causes/boot to grow

The solution is to remove the unwanted kernel, and then step:

To view all installed cores

dpkg--get-selections |grep Linux-image

View the currently used kernel

Uname-a

Remove the kernel that is currently in use

sudo apt-get purge linux-image-xxx corresponds to the same version, there should be two files deleted.
There is incomplete uninstall (hint), can be removed with sudo apt-get autoremove.

Clean up the/usr/src directory and delete the kernel directory you have uninstalled

Linux/boot cleanup