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

Table of Contents

Introduction

When enabling vSphere High Availability (HA) on a cluster running vSphere 8, you may encounter the error:

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

This issue prevents HA from being enabled and is commonly caused by certificate trust or agent communication problems between ESXi hosts and vCenter.

In this article, we explain the root cause and walk through a safe, step-by-step resolution.

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  • Corrupted or outdated ESXi host certificates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:

  1. Go to Cluster Settings

  2. Disable vSphere HA

  3. 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:

  1. Enable SSH

  2. Log in as root

  3. 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

Awid Dashtgoli
Awid Dashtgoli