Here’s a fix for the issue “errors and long delays in adding a single-node cluster (i.e. a 1 node cluster) under management in Virtual Machine Manager. Error that’s displayed in console is Warning (13926) that all of the nodes couldn’t be contacted.” This issue stems from the fact that VMM has an overcommitted property for each cluster. By default, a single-node cluster’ll always be overcommitted since any failure in that single node will cause entire cluster and its VMs to go down. There really are two workarounds for this issue: 1. Set the node reserve failure to 0 in the cluster properties. Unfortunately this can only be modified once the cluster has been brought under management by VMM. 2. Add a second temporary node to the cluster simply for the purposes of adding it to VMM. Then the second node can be removed.