We have been receiving this error when using the plan:
System.NullReferenceException: Object reference not set to an instance of an object
This error message may point to an issue with the connection between the database server and the application. Please ensure your on site IT investigates connection issues with the system. Please try the following:
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'