Cannot install the vCenter Server agent service: "Unknown installer error"

Products

• VMware vSphere ESXi

Issue/Introduction

ESXi host is unable to configure vSphere HA with the below error.

Cannot install the vCenter Server agent service: "Unknown installer error"

/var/run/log/esxupdate.log

2025-03-18T06:06:23Z esxupdate: 2126313: Transaction: INFO: Final list of VIBs being installed:
2025-03-18T06:06:23Z esxupdate: 2126313: esxupdate: ERROR: An esxupdate error exception was caught:
2025-03-18T06:06:23Z esxupdate: 2126313: esxupdate: ERROR: Traceback (most recent call last):
2025-03-18T06:06:23Z esxupdate: 2126313: esxupdate: ERROR:   File "/lib64/python3.8/site-packages/vmware/esximage/Utils/HostInfo.py", line 225, in _getFileSystemList
2025-03-18T06:06:23Z esxupdate: 2126313: esxupdate: ERROR:     return runCli(cmd, True)
2025-03-18T06:06:23Z esxupdate: 2126313: esxupdate: ERROR:   File "/lib64/python3.8/site-packages/esxutils.py", line 220, in runCli
2025-03-18T06:06:23Z esxupdate: 2126313: esxupdate: ERROR: esxutils.EsxcliError: Errors:
2025-03-18T06:06:23Z esxupdate: 2126313: esxupdate: ERROR: Unable to complete Sysinfo operation.  Please see the VMkernel log file for more details.: Vmkernel module necessary for this vsi call not loaded

++ We may also see an incorrect version of the fdm VIB on the ESXi host.

Cause

Issue appears to be caused by nfsclient and nfs4client modules failing to load, and vmkernel does not receive the vsi calls required to complete the update.

Resolution

Please apply the below steps to workaround the issue: 

1. Log into the ESXi through SSH/Putty as root

2. Run the below commands: 

esxcli system module load --force --module nfsclient

esxcli system module load --force --module nfs41client

3. Reconfigure HA.