Random reboots on 20.04 LTS
Solution 1:
I finally was able to fix it. It turns out it was the "ACPI bios error" who was rebooting the PC.
I fixed it by editing the configuration file for GRUB:
Open the file as root, for example by running
sudoedit /etc/default/grub
Change the line beginning GRUB_CMDLINE_LINUX_DEFAULT= to include the parameter libata.noacpi=1, so that after your edit it says, for example
GRUB_CMDLINE_LINUX_DEFAULT="libata.noacpi=1"
Save the file and exit, then run this command:
sudo update-grub
Reboot and it should work fine.