Please refer to the following steps on how to upgrade VMware vCenter Virtual Appliance (VCSA) 6.0 which do NOT have web console acccess (Port 5480) to 6.0 U3 in Command Line
SSH to VCSA 6.0 and go to Shell
vpxd -v VMware VirtualCenter 6.0.0 build-2656761
Go to https://my.vmware.com/group/vmware/patch#search to download VMware-vCenter-Server-Appliance-126.96.36.199500-7977753-patch-FP.iso
Attached the downloaded IOS to VCSA 6.0
Command> software-packages install --iso --acceptEulas [2018-06-01T04:02:00.152] : Staging software update packages from ISO [2018-06-01T04:02:00.152] : ISO mounted successfully [2018-06-01 04:02:00,166] : Running pre-stage script..... [2018-06-01T04:02:01.152] : Verifying staging area [2018-06-01T04:02:01.152] : Validating software update payload [2018-06-01T04:02:01.152] : Validation successful [2018-06-01 04:02:01,481] : Processing software packages in update payload 234/234 [2018-06-01T04:02:26.152] : ISO unmounted successfully [2018-06-01T04:02:26.152] : (234) packages staged successfully [2018-06-01 04:02:26,944] : Running test transaction .... [2018-06-01 04:02:35,962] : Running pre-install script..... [2018-06-01T04:04:05.152] : Services stopped. [2018-06-01 04:04:05,165] : Upgrading software packages .... [2018-06-01 04:10:31,861] : Running post-install script..... [2018-06-01T04:10:36.152] : Packages upgraded successfully, Reboot is required to complete the installation.
Reboot the VCSA 6.0 and verify it had been upgraded to U3e successfully
vpxd -v VMware VirtualCenter 6.0.0 build-7924804
You should be able to access to https://VCENTER:5480 Web Console now.