Testing the 4.3 to 4.4 migration... what I describe here is facts is mostly observations and conjecture, could be wrong, just makes writing easier... While 4.3 seems to maintain a default emulated machine type (pc-i440fx-rhel7.6.0 by default), it doesn't actually allow setting it in the cluster settings: Could be built-in, could be inherited from the default template... Most of my VMs were created with the default on 4.3. oVirt 4.4 presets that to pc-q35-rhel8.1.0 and that has implications: 1. Any VM imported from an export on a 4.3 farm, will get upgraded to Q35, which unfortunately breaks things, e.g. network adapters getting renamed as the first issue I stumbled on some Debian machines 2. If you try to compensate by lowering the cluster default from Q35 to pc-i44fx the hosted-engine will fail, because it was either built or came as Q35 and can no longer find critical devices: It evidently doesn't take/use the VM configuration data it had at the last shutdown, but seems to re-generate it according to some obscure logic, which fails here. I've tried creating a bit of backward compatibility by creating another template based on pc-i440fx, but at the time of the import, I cannot switch the template. If I try to downgrade the cluster, the hosted-engine will fail to start and I can't change the template of the hosted-engine to something Q35. Currently this leaves me in a position where I can't separate the move of VMs from 4.3 to 4.4 and the upgrade of the virtual hardware, which is a different mess for every OS in the mix of VMs. Recommendations, tips anyone? P.S. A hypervisor reconstructing the virtual hardware from anywhere but storage at every launch, is difficult to trust IMHO.