Unable to determine a valid ordering for dependent operations

Question

This is my model

public string Content { get; set; }  public Faq Reply { set; get; }  public int? ReplyId { get; set; }  public ICollection<Faq> Children { get; set; }  [ForeignKey("WriterId")] public virtual UserProfile Writer { get; set; }  public virtual int? WriterId { get; set; }  public Status Status { get; set; }  [ForeignKey("DepartmentId")] public virtual Department Department { get; set; }  public virtual int? DepartmentId { get; set; } 

And this is my error

Unable to determine a valid ordering for dependent operations. Dependencies may exist due to foreign key constraints, model requirements, or store-generated values.

Answer 1

Another possible cause of this is if the foreign key property is set incorrectly.

For example, this can happen in the following scenario:

1. DepartmentId is set to zero or any other value that isn't a valid foreign key.
2. Department is either null or it is a Department object that contains a null value for its own DepartmentId property.
3. This configuration will cause Entity Framework to fail because it tries to find a Department that has a primary key of zero, which probably won't exist.

I ran into this exception once when I mapped one object to another and I incorrectly set the foreign key to zero instead of setting it to null.

I can't say that this configuration is what is causing your exception without seeing the actual values of the properties, but it is one possibility.