This blog shows you the workaround for the error “cannot convert null to ‘system.datetime’ because it is a non-nullable value type” especially with you are working with SSIS project.
Declare the header
In Database Timestamp field you write.
Row.ShiftTimeOut = (DateTime)SqlDateTime.Null;
It will not be null in the database but it will be 1900-01-01 00:00:00:00.