VMware Update Manager (VUM) encounters an issue when trying to remediate a three node vSphere HA cluster when one node is in maintenance mode

Products

• VMware vSphere ESXi

Issue/Introduction

The remediation workflow fails at the "Remediate entity" step.

The error is -

VMware vSphere Lifecycle Manager had an unknown error. Check the event logs for details.

The description is -

Current progress of remediation: 0 hosts completed successfully, 1 hosts completed with errors, 0 hosts are being remediated, 0 hosts are waiting to start remediation, and 0 hosts could not enter maintenance mode and are waiting retry

Cannot remediate host host_fqdn because it cannot enter maintenance mode

Environment

vSphere 8.x

Cause

If a three node vSphere HA cluster has one node in maintenance mode, then it only has two active nodes.

As such, it is then (in effect) temporarily a two node vSphere HA cluster - and is thus subject to the constraints of such a cluster.

See the Additional Information section below for more context.

Resolution

Take the one node that is in maintenance mode out of maintenance mode, try to remediate the cluster again.

The expectation is that the cluster remediation will be successful this time.

Additional Information

For additional context, see this article - 

https://knowledge.broadcom.com/external/article?articleNumber=320045