To change the status of a Running Task use the fail-tasks command of the cell management tool on one Cell in the cluster after shutting down the Cloud Director service on all Cells.
Details on how to use the fail-tasks command are outlined in the Cloud Director documentation here, Update the Failure Status of a Task .
The Cloud Director service can be started again on the Cells after running the command.
If issues persist with the upgrade after taking these steps please open a Support Request with VMware Support.