6.7

Table Of Contents
Cause
When you add a host to vCenter Server, and vCenter Server already trusts the host's SSL certificate,
VPX_HOST.EXPECTED_SSL_THUMBPRINT is not populated in the vCenter Server database. vSphere HA
obtains the host's SSL thumbprint from this field in the database. Without the thumbprint, you cannot
enable vSphere HA.
Solution
1 In the vSphere Web Client, disconnect the host that has custom SSL certificates installed.
2 Reconnect the host to vCenter Server.
3 Accept the host's SSL certificate.
4 Enable vSphere HA on the host.
Troubleshooting Hosts
The host troubleshooting topics provide solutions to potential problems that you might encounter when
using your vCenter Servers and ESXi hosts.
Troubleshooting vSphere HA Host States
vCenter Server reports vSphere HA host states that indicate an error condition on the host. Such errors
can prevent vSphere HA from fully protecting the virtual machines on the host and can impede vSphere
HA's ability to restart virtual machines after a failure. Errors can occur when vSphere HA is being
configured or unconfigured on a host or, more rarely, during normal operation. When this happens, you
should determine how to resolve the error, so that vSphere HA is fully operational.
vSphere HA Agent Is in the Agent Unreachable State
The vSphere HA agent on a host is in the Agent Unreachable state for a minute or more. User
intervention might be required to resolve this situation.
Problem
vSphere HA reports that an agent is in the Agent Unreachable state when the agent for the host cannot
be contacted by the master host or by vCenter Server. Consequently, vSphere HA is not able to monitor
the virtual machines on the host and might not restart them after a failure.
Cause
A vSphere HA agent can be in the Agent Unreachable state for several reasons. This condition most
often indicates that a networking problem is preventing vCenter Server or the master host from contacting
the agent on the host, or that all hosts in the cluster have failed. This condition can also indicate the
unlikely situation that vSphere HA was disabled and then re-enabled on the cluster while vCenter Server
could not communicate with the vSphere HA agent on the host, or that the ESXi host agent on the host
has failed, and the watchdog process was unable to restart it. In any of these cases, a failover event is
not triggered when a host goes into the Unreachable state.
vCenter Server and Host Management
VMware, Inc. 201