Hmm…. an update to 5.5 already!
If you’re using the vCenter Server Appliance (vCSA) and have already upgraded from 5.1 to 5.5, then updating the appliance is a very simple process if your vCSA is able to connect out to the internet:
Note: this update process will reboot your vCSA so you will lose connectivity to your vCenter Server! Be warned!
Once rebooted, the vCenter Server should be assessible again.
If you are not connected to the internet, then you can download the update ISO file from your ‘My VMware’ portal.
Once downloaded (about 1.6GB), mount the ISO file to the vCSA VM and navigate to the Settings section under Update. Select Use CDROM Updates as the Update Repository, click Save Settings and then follow the instructions outlined above from Step 2.