Reboot during boot

[sabotage3d]

Hi,

I am getting this issue when I boot my machine and after the grub menu when I see the kubuntu logo it reboots. It happens often but not every time and I cannot get the log. Any advice on how to debug the issue would be appreciated.

[jlittle]

(Myself and another poster here have had stability issues with 17.10. I didn't often get reboots, but hangs. Some kind of corruption in the OS appears to me to be the culprit; maybe a bad update. The other poster reported a corrupt video driver. I moved to a clean install of bionic, 18.04, slightly early, and left it behind.)

You could turn off the logo, to see the boot messages. To do this, edit /etc/default/grub to remove the words "quiet splash" from the GRUB_CMDLINE_LINUX_DEFAULT line, so that it reads GRUB_CMDLINE_LINUX_DEFAULT=""
In a konsole maybe:

EDITOR=nano sudoedit /etc/default/grub
sudo update-grub

However, these days Kubuntu boots really quickly and if your computer is rebooting boot messages might fly past and be lost.