Hi
Yes I have performed step 11.
Perhaps I did not mention it, I can use vCenter on the secondary node with all components updated to 5.1 Update1 and everything works fine.
When I want to contiinue with the upgrade (on primary node) the starting of vCenter service fails with the error: Event 1000 VMware VirtualCenter server failed to start, Database version 511 is incompatible with this release of VirtualCenter.
regards