During the process of restoring the vCenter Server backup file in the vCenter Server Appliance, services in the appliance must restart. While they are restarting, your API client receives an error message.

You can write your client to trap the error, but you have no way to know when the Appliance services are running again. To determine when the restore process is complete, you must retry the API connection until it succeeds, then request the status of the job.