There are no other jobs. I've now spun up a completely separate, fresh install of XCP-ng 8.3 to test the symptoms mentioned in the OP. Steps taken Installed XCP-ng 8.3 Text console over SSH xe host-disable xe host-evacuate (not needed yet of course since it's a brand-new install) yum update Reboot Text console over SSH again Created local ISO SR xe sr-create name-label="Local ISO" type=iso device-config:location=/opt/var/iso_repository device-config:legacy_mode=true content-type=iso cd /opt/var/iso_repository wget # ISO for Ubuntu Server xe sr-scan uuid=07dcbf24-761d-1332-9cd3-d7d67de1aa22 XO Lite New VM Booted from ISO, installed Server Text console to VM over SSH apt update/upgrade installed xe-guest-utilities Installed XO from source (ronivay script) XO Import ISO for Ubuntu Mate New VM Booted from ISO, installed Mate apt update/upgrade xe-guest-utilities New CR backup job Nightly VMs: 1 (Mate) Retention: 15 Full: every 7 Exact same behaviour. After first (full) CR job run, additional (incremental) CR job runs results in one more 'unhealthy VDI'. I've engaged in no other shenanigans. Plain vanilla XCP-ng and XO. There are only two VMs on this host, the XO from source VM, and a desktop OS VM which is the only target of the CR job. There are zero exceptions in SMlog. What do you need to see?

@Andrew many thanks. As do I. See my OP. A failed build doesn't break XO. It leaves the previous successful build in place. My post wasn't to ask how to fix my problem, but to point out the issue to others who might care to know (see my last post). Cheers.