Check if helps: http://notes.doodzzz.net/2015/03/24/vsphere-6-0-home-lab-upgrade-issues-faced/
- At this point I clicked the lovely next buttons and started the upgrade (got a warning that the MSSQL Express database will be replaced with vPostgres of course) and suddenly after the wizard started extracting data from the vCenter 5.5 installation I got this error (Error attempting Backup PBM: Please check InvSvc upgrade logs for details) << The error implies that it is related to InvSvc (Inventory Services) but I did some research and confirmed that PBM is something related to the inventory services, I couldn’t but link this so the fact that I have generated a new SSL certificate for the inventory services and for some reason it is still using https://localhost/ to connect, so I did a little more digging on how to reset the vCenter Inventory Service database and found this VMware KB after following the 5.5 section, resetting the database and registering the Inventory Service with vCenter using the new FQDN all went well and the wizard continued.