how to roll back a kernel ubuntu 16.04

Question

I could not find this easily today so I am putting it here for other people, and myself in 6 months

How do you roll back a kernel in ubuntu LTS 16.04, answered below

Answer 1

do the following steps in order

1. ssh into the box
2. sudo su -
3. count the menu and submenu lines to get to the kernel you want to boot, indexed at 0
4. edit /etc/default/grub
5. change GRUB_DEFAULT=0 to GRUB_DEFAULT="M>N" and save
   • M is menu count
   • N is submenu count, the kernel you want to boot
   • ON 16.04 you start counting N when you get here: submenu 'Advanced options for Ubuntu'
6. update-grub
7. systemctl reboot
8. ssh in
9. uname -r to see if you booted to the right kernel
10. sudo su -
11. apt-get purge linux-headers-version_to_remove and linux-image-version_to_remove
12. edit /etc/default/grub and change to: GRUB_DEFAULT=0
13. systemctl reboot
14. ssh in and uname -r to see if you are good

orignal article https://www.calazan.com/how-to-set-an-older-kernel-version-as-the-default-in-grub-during-bootup-ubuntu-12-04/

If you do this wrong you may not be able to boot the box, be warned