We recently changed our NTP server, and I needed to update all or hosts and vCenters. I have a handy powershell script to update the ESXi hosts, but that script does not work on the vCenter servers. I log into the server using port 5480 to gain access to the vCenter Management. I login as root and notice that the time zone is UTC. I am in the Central time zone so I wanted to change it from UTC. Turns out if you do that it break everything. I had to learn this the hard way, and once I changed the time zone I was not able to log into vCenter. I had to then go back and change the time zone back to UTC to regain access. .