We have been receiving this error when using the plan:
System.NullReferenceException: Object reference not set to an instance of an object
You may see this error when using the plan in Orchestrate. It may indicate a connection issue between the database server and the application. Ask your IT team to investigate and work through the steps below.
1. Restart the SQL Service for the instance that Orchestrate runs on
2. Check that database statistics are up to date for the Orchestrate database. Details on how to do this can be found 'here'