VxRail: ESXi Host Failed to Enter Name Namespaces Maintenance Mode

Entering or exiting maintenance mode through the vSphere Web Client is not possible. 
This occurs after an upgrade or patch of the internal or external vCenter, to a version in the 7.0 family.

When connecting to vCenter through SSH or telnet and checking services, it returns:

service-control --status --all
STOPPED: wcp

vCenter vpxd.log:

WCP enterMaintenanceMode vAPI returns error: Error:
--> com.vmware.vapi.std.errors.unauthenticated
--> Messages:
--> vapi.security.authentication.invalid<Unable to authenticate user>

Failed to delete vAPI session. Error:
--> Error:
--> com.vmware.vapi.std.errors.unauthenticated
--> Messages:
--> vapi.security.authentication.invalid<Unable to authenticate user>

To resolve this issue: 

1. Create a Snapshot of the vCenter and then ssh to vCenter as root.
2. Create a backup of /etc/vmware/wcp/wcpsvc.yaml by command:

cp /etc/vmware/wcp/wcpsvc.yaml /etc/vmware/wcp/wcpsvc.yaml.bak

1. Change this line rhttpproxy_port: {rhttpproxy.ext.port2} in the above YAML file to rhttpproxy_port: 443   
2. Start the WCP-service with the command:

service-control --start wcp

If the above actions do not solve the issue, check Broadcom Article .