Updating DNS settings in SDDC Manager fails with group of hosts reported as "in Maintenance Mode"

Products

• VMware SDDC Manager

Issue/Introduction

• Trying to update DNS settings on VCF environment, the task failed reporting that a group of hosts are in maintenance mode, but they are working as expected in vSphere UI.
  In SDDC manager we can see the failed DNS update task and comparing to the hosts in the vSphere UI, they are not in maintenance mode.
• In the operations manager logs, we see the following:

DEBUG [vcf_om,a05f63a601674b47,37e2] [c.v.e.s.c.c.v.vsphere.VcManagerBase,om-exec-8] Finding host with fqdn esx001.example.com
DEBUG [vcf_om,a05f63a601674b47,37e2] [c.v.e.s.c.c.v.vsphere.VcManagerBase,om-exec-8] Finding host with fqdn esx001.example.com
ERROR [vcf_om,a05f63a601674b47,37e2] [c.v.e.s.c.c.v.vsphere.VcManagerBase,om-exec-8] Host esx001.example.com not found
WARN  [vcf_om,a05f63a601674b47,37e2] [c.v.v.v.c.h.i.HttpConfigurationCompilerBase$ConnectionMonitorThreadBase,om-exec-8] Shutting down the connection monitor.
ERROR [vcf_om,a05f63a601674b47,37e2] [c.v.v.s.s.v.SystemConfiguratorEntitiyStateValidator,om-exec-8] Error occurred while checking the maintenance mode state for the host esx001.example.com.

• When running the command esxcli system hostname get, the following output is shown:
  ESX001.example.com (uppercase)

Environment

VMware ESXi 7.0.3

Cause

The issue is caused by the SDDC manager requesting information from the ESXi hosts, but the hostnames are case sensitive and it cannot find the host. 

Resolution

This is a known bug and is resolved in ESXi 8.0.1. Please upgrade the hosts to ESXi 8.0.1 or higher.

Workaround:
Update the ESXi hostname to match the hostname case specified in the logs so they match the lookups originating from SDDC Manager.