VMware Update Manager limitation in 2-node vSphere HA cluster

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:

• When attempting a cluster remediation via VUM the task fails because the hosts can't be put into maintenance mode automatically.
• The following event is shown for the hosts: "Cannot remediate host <hostname> because it cannot enter maintenance mode."

Note: Disabling HA Admission Control does not work for this issue.

Cause

This behavior is per design, because if one host is placed into maintenance mode there would only be one host left and therefore HA wouldn't be able to perform a failover for VMs.

Resolution

Currently, there is no resolution.

Workaround:
​There are two workarounds available:

1. Manually place individual hosts into maintenance mode and perform the update via VUM per host.
2. Disable HA for the duration of the VUM cluster remediation.