RajeevVCP4 unfortunately, the same error has manifested with the 5.5 to 6.0 U1a upgrade.
vminst.log:
2019-07-24 15:45:51.772-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Database settings: Type='embedded', DSN='', User=''.
2019-07-24 15:45:51.772-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Processing pre-upgrade for component com.vmware.vco
2019-07-24 15:45:51.772-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Export disk req: 99 MB, Import disk req: 99 MB.
2019-07-24 15:45:51.772-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Adding 8230 as a whitelisted port.
2019-07-24 15:45:51.772-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Adding 8280 as a whitelisted port.
2019-07-24 15:45:51.772-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Adding 8281 as a whitelisted port.
2019-07-24 15:45:51.772-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Adding 8283 as a whitelisted port.
2019-07-24 15:45:51.772-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Adding 8287 as a whitelisted port.
2019-07-24 15:45:51.772-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Processing pre-upgrade for component com.vmware.is
2019-07-24 15:45:51.772-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Export disk req: 209 MB, Import disk req: 314 MB.
2019-07-24 15:45:51.772-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Adding 10080 as a whitelisted port.
2019-07-24 15:45:51.772-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Adding 10443 as a whitelisted port.
2019-07-24 15:45:51.772-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Adding 10111 as a whitelisted port.
2019-07-24 15:45:51.773-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Adding 10109 as a whitelisted port.
2019-07-24 15:45:51.773-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Ignoring destination port invsvc.int.http because it is not an external port
2019-07-24 15:45:51.773-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Processing pre-upgrade for component upgrade_framework
2019-07-24 15:45:51.773-04:00| vcsInstUtil-3018519| I: ParsePreUpgradeOutput: Export disk req: 0 MB, Import disk req: 0 MB.
2019-07-24 15:45:51.773-04:00| vcsInstUtil-3018519| I: PitCA_MessageBox: Displaying message: "Error: Unable to fetch or parse VC URL from vCenter ServiceInstance!
Resolution: VC URL in vCenter ServiceInstance is unreadable. The vCenter Service may not be reachable. Please contact customer support and submit a support bundle."
2019-07-24 15:47:26.581-04:00| vcsInstUtil-3018519| I: Leaving function: ParsePreUpgradeOutput
CollectRequirements_com.vmware.vxpd:
2019-07-24T19:44:23.138Z INFO vpxd.vpxd_export Cert has no Host IPv4 entries
2019-07-24T19:44:23.138Z WARNING vpxd.vpxd_export VPXD Certificate is invalid and will be replaced.
2019-07-24T19:44:23.138Z WARNING vpxd.vpxd_export Certificate Req Mismatch Errors or Warnings present.
2019-07-24T19:44:23.138Z INFO vpxd.vpxd_export Heartbeat port from registry is 902
2019-07-24T19:44:23.141Z INFO vpxd.vpxd_export Http and Https port from registry are 80, 443
2019-07-24T19:44:23.142Z INFO vpxd.vpxd_export Found SDK Node with port 8085
2019-07-24T19:44:23.142Z INFO vpxd.vpxd_export Found SDKTunnel Node with port 8089
2019-07-24T19:44:23.142Z INFO vpxd.vpxd_export VPXD Source ports are: ['8085', '8089', u'80', u'443', '389', '636', u'902']
2019-07-24T19:44:23.142Z INFO vpxd.vpxd_export VPXD Destination Ports are: ['8085', '8089', u'80', u'443'], 902
2019-07-24T19:44:23.144Z INFO vpxd.vpxd_export SSO Admin Uri: https://FQDN:7444/sso-adminserver/sdk/vsphere.local
2019-07-24T19:44:23.144Z INFO vpxd.vpxd_export SSO Extra Arguments are {'vpxd.sso.port': '7444', 'vpxd.sso.host': 'FQDN', 'vpxd.sso.admin.url': 'https://FQDN:7444/sso-adminserver/sdk/vsphere.local', 'vpxd.sso.sts.url': 'https://FQDN:7444/sts/STSService/vsphere.local', 'vpxd.sso.group.url': 'FQDN:7444/sso-adminserver/sdk/vsphere.local'}
2019-07-24T19:44:23.144Z ERROR transport.local NOT FOUND: Cannot read registry. Error: [Error 2] The system cannot find the file specified
2019-07-24T19:44:23.144Z WARNING vpxd.vpxd_export Exception reading Netdumper port from registry.
2019-07-24T19:44:23.145Z WARNING vpxd.vpxd_export Netdumper 'NotInstalled'. Netdumper config file C:\ProgramData\VMware\VMware ESXi Dump Collector\vmconfig-netdump.xml does not exist!
2019-07-24T19:44:23.145Z INFO vpxd.vpxd_export Netdumper Source ports are: []
2019-07-24T19:44:23.145Z INFO vpxd.vpxd_export Using 5.5.0.15337 WebClient registry path
2019-07-24T19:44:23.148Z INFO vpxd.vpxd_export WebClient ports from registry: [u'9443', u'9090', u'9011']
2019-07-24T19:44:23.148Z INFO vpxd.vpxd_export Using 5.5 WebClient config path
2019-07-24T19:44:23.148Z INFO vpxd.vpxd_export Using WebClient config path C:\Program Files\VMware\Infrastructure\vSphereWebClient\server\configuration\tomcat-server.xml
2019-07-24T19:44:23.148Z INFO vpxd.vpxd_export WebClient ports from config file: ['9443', '9090', '9011']
2019-07-24T19:44:23.148Z INFO vpxd.vpxd_export Webclient ports: [u'9443', u'9090', u'9011']
2019-07-24T19:44:23.150Z INFO vpxd.vpxd_export WebClient Source ports are: [u'9443', u'9090', u'9011']
2019-07-24T19:44:23.150Z INFO vpxd.vpxd_export SPS Source ports : ['31010', '31100']
2019-07-24T19:44:23.151Z INFO vpxd.vpxd_export PBM Source ports : ['8190', '8191']
2019-07-24T19:44:23.151Z INFO vpxd.vpxd_export SMS Source ports : ['32010', '32100']
2019-07-24T19:44:23.151Z INFO vpxd.vpxd_export Consolidated SPS service ports : ['31010', '31100', '8190', '8191', '32010', '32100']
2019-07-24T19:44:23.157Z INFO vc_connector Vpxd http port is configured to: 80
2019-07-24T19:44:23.157Z INFO vc_connector Vpxd https port is configured to: 443
2019-07-24T19:44:23.611Z ERROR vpxd.vpxd_export Exception: 302 Moved Temporarily. Unable to fetch or parse VCenter URL from Services List.
2019-07-24T19:44:23.612Z ERROR vpxd.vpxd_export VC Hostname Req Mismatch Error Spec present.
Again, I'm baffled to where this "302 Moved Temporarily" and "VC Hostname Req Mismatch" errors are coming from but I'm not able to proceed with the 6.0 U1a upgrade