Not enough resources to failover a VM.
vSphere HA does not have sufficient resources to complete VM failover in a VMware vSphere Cluster. The problem can have the following causes:
- Hosts in the cluster are disconnected, not responding or are placed to the maintenance mode.
- Hosts have a vSphere HA error.
- Some of VMs in the cluster have much more memory and CPU resources reserved than other VMs.
- There are no free slots in the cluster.
- Check hosts connectivity and state.
- Re-configure VMs to balance resource reservation.
- Make sure that there are free slots in the cluster.
Refer to this VMware KB article for more information about VM failover problems.