SystemError during Ubuntu upgrade: no linux-headers-4.40-166 archive

Hi there,

What I would suggest is that you run these following commands:

sudo apt autoremove
sudo apt purge linux-headers-4.4.0-166
sudo apt install --reinstall linux-headers-generic

This will remove the package and install the current one. When you do these kinds of upgrades there is always the possibility of something going wrong, so it is good to have a backup that you could use to revert to a working state of your server.

Let me know how this goes.

Regards, Boyan