This weekend I was installing updates on an HyperV cluster by entering the nodes into the maintenance mode one by one from Virtual Machine Manager. I know that updates can be done automatically using VMM or Cluster Aware Updating, but it’s not implemented for the moment.
Two of the hosts were giving the following error when entering into the maintenance mode: “Error (10434) No suitable host is available for migrating the existing highly available virtual machine. Recommended Action: Either improve the host ratings for the other hosts within the same cluster, and then try the operation again, or do not migrate the virtual machines”
If you will search for this error you’ll find many recommendations but none of them were helping me out. So, I decided to start migrating the VMs one by one from the host, and luckily the first one that I tried to migrate was causing the issue. Someone created a Linux Generation 2 VM and set the operating system to a 32bit version and it’s not possible to Live Migrate a Gen2 VM with a 32bit OS.
After I changed the VM Operating System to 64bit from the properties I was able to enter into maintenance mode the host.