I had an issue with upgrading some VMs from Ubuntu 20.04 to 22.04 in XCP-NG. Upon Upgrade the VMs would shutdown and not reboot to Linux. Changing the Boot Properties from PV Boot to HVM did not fix the issue. However reinstalling GRUB on the servers did fix the issue. It looked like this but it was not.
https://xcp-ng.org/forum/topic/7474/cant-boot-ubuntu-22-04-lts-after-release-update/12
- Boot VM to Ubuntu Server 22.04 Install Disk
- Enter Terminal
- Mount the Disk on the VM
sudo mount /dev/xvda1 /mnt - Upgrade GRUB on the VM
sudo grub-install --boot-directory=/mnt/boot /dev/xvda - Reboot
SOURCE: https://help.ubuntu.com/community/Grub2/Installing#via_the_LiveCD_terminal