Hello all. I am currently a student working in a lab environment and am having some interesting issues with my ESXI upgrade.
A little more info about my environment, I have two Dell Poweredge R630's with ESXI 6.5 installed. I have two Vcenter 6.7 servers, one on each host and one 6.5 VCenter on a single host. These are not Windows boxes, They are the ESXI version (I dont know exactly what to call it).
So I was planning to upgrade each host from the VCenter on the opposing server. I uploaded the ESXI 6.7 ISO to Update Manager and created a baseline. I was entering the ESXI host into maintenance mode when Update Manager became completely blank. I could see the tabs for Baseline, updates, ESXI ISOs but there was nothing underneath, no menu or anything so I could not remediate the host as I planned.
After many refreshes of the web browser we decided to restart the VCenter server which is where we ran into many more problems. now we get the "503 Service Unavailable" which I usually brush off as just the server starting up but it has been well over an hour (I also restarted the 6.5 server and it has already come back up). I am able to console to the VCenter host via ESXI and can SSH to it as well.
root@photon-machine [ ~ ]# service-control --status
Running:
applmgmt lwsmd vmafdd vmcad vmdird vmdnsd vmonapi vmware-analytics vmware-cis-license vmware-eam vmware-pod vmware-postgres-archiver vmware-rhttpproxy vmware-statsmonitor vmware-sts-idmd vmware-stsd vmware-vapi-endpoint vmware-vmon vmware-vpostgres vsphere-client vsphere-ui
Stopped:
pschealth vmcam vmware-cm vmware-content-library vmware-imagebuilder vmware-mbcs vmware-netdumper vmware-perfcharts vmware-rbd-watchdog vmware-sca vmware-sps vmware-updatemgr vmware-vcha vmware-vpxd vmware-vpxd-svcs vmware-vsan-health vmware-vsm vsan-dps
I used this link and ran update manager and ran option 3
I got a few errors but one that caught my eye was:
Error while reverting certificate for store : MACHINE_SSL_CERT
My theory so far are that I either did not get the correct 6.7 VCenter ISo (Do i need 6.7 u2?) or that the hostnames are being weird with having multiple VCenters. I always named the FQDN to be the IP address but in ESXI the hostname is listed as Photon-machine.
Wondering if anyone else has experienced my issues with VCenter and Update Manager?
Thanks in advance
James
Edit: Currently trying to do an upgrade via command line of the ESXI host. I originally thought I could not enable SSH without being at the console.
Edit#2: Got it upgraded 
with the offline bundle and SSH. Definitely a learning experience. Now time to see if my VCenter servers are back. I will mark the post as answered.
Message was edited by: James Bowman