Fix: “Error Installing HA Components Failed” in vSphere 8

Issue

					Error installing HA components. Failed to install HA components on the hosts.

What Causes This Error?

The HA installation process relies on vCenter deploying and configuring HA agents (fdm) on all ESXi hosts in the cluster. This process can fail due to:

Corrupted or outdated ESXi host certificates
Certificate trust mismatch between vCenter and ESXi
Leftover HA agent files from a previous configuration
Management service communication issues
Interrupted upgrades or host reprovisioning

As a result, vCenter cannot successfully install or validate the HA components.

Verify the Exact Error

Start by checking the vSphere Client task details when HA fails to enable.
You’ll usually see errors referencing:

fdm
Install agent
Trust relationship
Cannot verify host certificate

This confirms the issue is agent- or certificate-related.

Solution

Disable HA on the Cluster (If Partially Enabled)

If HA is in a failed or partial state:

Go to Cluster Settings
Disable vSphere HA
Wait until the configuration fully completes

This ensures a clean baseline before remediation.

Restart ESXi Management Services

On each ESXi host in the affected cluster:

Enable SSH
Log in as root
Restart management agents:

					/etc/init.d/hostd restart
/etc/init.d/vpxa restart

This clears stale agent communication issues.

Remove Old HA Agent Files (If Present)

On each ESXi host, check for existing HA configuration remnants:

					ls -l /etc/opt/vmware/fdm

If the directory exists, stop services and remove it:

					/etc/init.d/hostd stop
/etc/init.d/vpxa stop
rm -rf /etc/opt/vmware/fdm
/etc/init.d/hostd start
/etc/init.d/vpxa start

Refresh Host Certificates (Most Common Fix)

Refresh Certificates via vCenter:

In the vSphere Client, select the host
Go to Configure → System → Certificate
Click Renew or Refresh Certificates
Reconnect the host if prompted