Error: "Cannot find vSphere HA master agent" and Looping HA Configuration Tasks After vCenter Server Upgrade
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Error: "Cannot find vSphere HA master agent" and Looping HA Configuration Tasks After vCenter Server Upgrade

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Article ID: 444836

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Updated On:

Products

VMware vSphere ESXi

Issue/Introduction

  • The host HA state reports as "Uninitialized".
  • vCenter displays the error: "Cannot find vSphere HA master agent.
  • Network connectivity (port 8182) and DNS resolution to the vCenter FQDN are fully functional.
  • Checking the host packages via CLI shows the vmware-fdm VIB is stuck at the older version.
  • The esxupdate.log contains the message:

    LiveImageInstaller: DEBUG: Only reboot-required installations are possible right now as a reboot-required installation has been done.

Environment

vSphere 8.x

Cause

  • This issue occurs when the affected ESXi hosts have a pending reboot from a previous system change, such as staging a patch, updating firmware, or installing a driver.
  • When an ESXi host is in a "pending reboot" state, the local package manager (esxupdate) places a strict lock on live installations. This lock silently blocks vCenter from dynamically uninstalling the old Fault Domain Manager (vmware-fdm) agent and pushing the new version required to communicate with the upgraded vCenter. Because the installation fails in the background and rolls back, the HA cluster election never completes.

Resolution

To clear the live-installation lock and allow vCenter to update the HA agent, the affected hosts must be rebooted.

  • Disable vSphere HA:
    In the vSphere Client, navigate to the Cluster > Configure > vSphere Availability.
    Click Edit, uncheck the box to disable vSphere HA, and click OK. Wait for the "Unconfigure HA" tasks to complete.
  • Enter Maintenance Mode:
    Migrate any running virtual machines off the affected ESXi hosts and place them into Maintenance Mode.
  • Reboot the Hosts:
    Restart each of the affected ESXi hosts. This will formally clear the esxupdate pending-reboot lock.
  • Exit Maintenance Mode:
    Once the hosts are back online and connected to vCenter, take them out of Maintenance Mode.
  • Enable vSphere HA:
    Return to your Cluster > Configure > vSphere Availability settings and enable vSphere HA.
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