Instead of performing an in-place upgrade of Orchestrator, you might want to use a different machine for your upgrade.

The vCenter Server 5.0 installation media includes a data migration tool that you can use to migrate Orchestrator and vCenter Server configuration data from your existing installation on a 32-bit vCenter Server machine to a new installation on the 64-bit machine. This data migration tool is not supported for vCenter Server 5.1 and Orchestrator 5.1. You cannot directly migrate an existing Orchestrator installation to a different machine during an upgrade to version 5.1. You can migrate an existing Orchestrator installation to a different machine during the upgrade to version 4.2, and then perform an in-place upgrade from version 4.2 to version 5.1. See the version 4.2 of Installing and Configuring VMware vCenter Orchestrator documentation.