Diagnostics for VMware Cloud Foundation: vCenter Health: vSphere High Availability - Configuration error

Products

• VCF Operations

Issue/Introduction

The error Config error, VcCannotFindMasterEvent occurs when a vSphere HA agent (FDM - Fault Domain Manager) on a specific host is unable to locate or connect to the Primary (Master) host in the cluster.

This results in the vCenter UI reporting: "Cannot find vSphere HA master agent" or "vSphere HA agent for this host has an error".

Environment

VCF Operations 9.1

vSphere 8.x / 9.x

Cause

The election of a Primary host has failed or the agent communication is broken due to:

• Network Partitioning: Management network isolation or incorrect VLAN tagging.
• Agent Corruption: FDM VIB issues after a host update or VCF LCM (Life Cycle Management) operation.
• Time Drift: NTP desynchronization between vCenter and ESXi hosts.
• DNS Issues: Failure to resolve FQDN between cluster members.

Resolution

To resolve this issue, perform the following steps in sequence:

Host Reconfiguration: Right-click the affected host and select vSphere HA > Reconfigure for vSphere HA.

Network Validation: Verify that the host can ping the Management IP of other hosts and vCenter. Ensure ports 443 and 902 are open.

NTP Sync: Ensure all hosts and vCenter are synchronized to the same NTP source.

Service Restart: If the issue persists, restart the management agents via SSH:

services.sh restart (or /etc/init.d/hostd restart && /etc/init.d/vpxa restart).

Cluster Toggle: As a last resort, turn vSphere HA OFF and then ON at the cluster settings level to force a global agent refresh.

For detailed manual VIB uninstallation (only for ESXi < 9.0) and deep troubleshooting, refer to the following KB: https://knowledge.broadcom.com/external/article/313044/

Additional Information

VCF Impact: A degraded HA state may block SDDC Manager pre-checks and automated upgrades.

Logs: Check /var/run/log/fdm.log on the affected host for specific election errors.