Try to boot in safe mode then.

What does the memory min/max settings look like in the advanced tab of those VM's? You could try to set the dynamic min/max to same values. Could very well be that your guest OS doesn't handle it properly when host is trying to dynamically adjust the available VM memory. Although this shouldn't happen (afaik) if there's plenty of memory available on the host, but worth a try at least.

@davemcl HI !

You can use this:

qemu-img convert -O vpc proxmox-disk.qcow2 `uuidgen`.vhd scp thegenerateduuid.vhd ip.xcp-ng.server:/run/sr-mount/uuid-of-your-SR

Then with XO create a VM and attach the disk

It should be working 🙂