Symptoms
Linux Virtual Machine on Virtuozzo Hybrid Server 7.5 does not boot with "no bootable option was found".
Cause
Grub EFI boot entry corruption, can happen to a virtual machine or physical server for various reasons, such as ungraceful shudown or FS corruption.
For the EFI Linux VMs that were created on earlier versions of Virtuozzo Hybrid Server and then moved/migrated to Virtuozzo Hybrid Server 7.5 Update 5 the reason can be non-default (manually changed) EFI settings that interfered the upgrade of the EFI flash size of the VMs on this version.
Resolution
On the example of the Debian OS.
0. Make sure you have a backup of the VM before making any changes.
1. In VNC hit any key to enter setup and select "Boot Maintenance Manager" in EFI Setup:
2. Next select "Boot From File":
3. Choose disk:
4. Browse path \EFI\debian\ :
5. Select "grubx64.efi" file for booting:
6. Boot OS and reinstall grub to create EFI boot record:
Note: "/dev/sda" below is just an example, you need to choose the system disk on this step and that may be another disk with another name in your VM