The vSphere HA agent on a host is in the Uninitialized state for a minute or more. User intervention might be required to resolve this situation.
vSphere HA reports that an agent is in the Uninitialized state when the agent for the host is unable to enter the run state and become the primary host or to connect to the primary host. Consequently, vSphere HA is not able to monitor the virtual machines on the host and might not restart them after a failure.
A vSphere HA agent can be in the Uninitialized state for one or more reasons. This condition most often indicates that the host does not have access to any datastores. Less frequently, this condition indicates that the host does not have access to its local datastore on which vSphere HA caches state information, the agent on the host is inaccessible, or the vSphere HA agent is unable to open required firewall ports. It is also possible that the ESXi host agent has stopped.
Search the list of the host's events for recent occurrences of the event vSphere HA Agent for the host has an error. This event indicates the reason for the host being in the uninitialized state. If the condition exists because of a datastore problem, resolve whatever is preventing the host from accessing the affected datastores. If the ESXi host agent has stopped, you must restart it. After the problem has been resolved, if the agent does not return to an operational state, reconfigure vSphere HA on the host.