Symptoms
It is not possible to migrate EFI VM from Virtuozzo Hybrid Server 7.5 Update 5 or later version to the Virtuozzo Hybrid Server 7.5 Update 4 or earlier versions of the Virtuozzo Hybrid Server, the following error is shown:
# prlctl migrate MyVM root@
...
Failed to migrate the VM: Unable to migrate the virtual machine. The virtual machine or the source and destination servers do not comply with the migration requirements.
Resolution
EFI flash size for the newly created and existing VMs had been changed in Virtuozzo Hybrid Server 7.5 Update 5 , migration of such VMs to the previous version of Virtuozzo Hybrid Server is prohibited due to this.
Additional info
How to manually update nvram for the certain EFI boot VM after update to VHS7.5 Update 5