Today I got the following error when working with the Linq to Sql dbml file: "System.InvalidOperationExc... Incorrect AutoSync specification for member 'xxxxx'." The problem involved the primary key "NationId" in the following image: When you right-click on NationId and select properties, you see this in the Properties window: The problem is that the auto-sync property should be "OnInsert" instead of "Always". However, I have not figured out how to make "OnInsert" the default when the view/table ......