Schema specified is not valid. Errors: The relationship was not loaded because the type is not available

Question

I wish to reference the OrderAddress model twice in my Order model; once as a ShippingAddress and once as a Billing

Answer 1

In my case I had this error because I made another partial class with the same name as the class generated by entity framework. Except mine did not matche the case. For example:

public partial class Vehicle
{
    public string Name { get; set; }
    public string Make { get; set; }
    ...
}

public partial class VEhicle
{
    public override bool Equals(object obj)
    {
       ...
    }
}

Answer 2

In my case, the problem is because of table name conflict.

I have another edmx model that has some tables with similar names. Just click on the table in the designer, then in the properties change the name to something different!