The property 'Id' is part of the object's key information and cannot be modified

Question

i\'m using Entity Framework 4.0 and having a silly problem that i can\'t figure out.

I have two tables:

1. Contact: Id (primary key), Value, ContactTypeId

Answer 1

I had this happening when I was editing related objects from two separate contexts at the same time. Example:

DataContext ctxA = new DataContext();
DataContext ctxB = new DataContext();

Author orwell = new Author {Name = "George Orwell" };
ctxA.Add(orwell);
ctxB.Add(new Book {Name = "1984", Author = orwell});

ctxA.SaveChanges();
ctxB.SaveChanges();

My case was a little bit more convoluted (as this is obviously quite stupid) but in essence this was causing the error in my case.