[.net] Introducing FOREIGN KEY constraint may cause cycles or multiple cascade paths - why?

I've been wrestling with this for a while and can't quite figure out what's happening. I have a Card entity which contains Sides (usually 2) - and both Cards and Sides have a Stage. I'm using EF Codefirst migrations and the migrations are failing with this error:

Introducing FOREIGN KEY constraint 'FK_dbo.Sides_dbo.Cards_CardId' on table 'Sides' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.

Here's my Card entity:

public class Card
{
    public Card()
    {
        Sides = new Collection<Side>();
        Stage = Stage.ONE;
    }

    [Key]
    [Required]
    public virtual int CardId { get; set; }

    [Required]
    public virtual Stage Stage { get; set; }

    [Required]
    [ForeignKey("CardId")]
    public virtual ICollection<Side> Sides { get; set; }
}

Here's my Side entity:

public class Side
{
    public Side()
    {
        Stage = Stage.ONE;
    }

    [Key]
    [Required]     
    public virtual int SideId { get; set; } 

    [Required]
    public virtual Stage Stage { get; set; }

    [Required]
    public int CardId { get; set; }

    [ForeignKey("CardId")]
    public virtual Card Card { get; set; }

}

And here's my Stage entity:

public class Stage
{
    // Zero
    public static readonly Stage ONE = new Stage(new TimeSpan(0, 0, 0), "ONE");
    // Ten seconds
    public static readonly Stage TWO = new Stage(new TimeSpan(0, 0, 10), "TWO");

    public static IEnumerable<Stage> Values
    {
        get
        {
            yield return ONE;
            yield return TWO;
        }

    }

    public int StageId { get; set; }
    private readonly TimeSpan span;
    public string Title { get; set; }

    Stage(TimeSpan span, string title)
    {
        this.span = span;
        this.Title = title;
    }

    public TimeSpan Span { get { return span; } }
}

What's odd is that if I add the following to my Stage class:

    public int? SideId { get; set; }
    [ForeignKey("SideId")]
    public virtual Side Side { get; set; }

The migration runs successfully. If I open up SSMS and look at the tables, I can see that Stage_StageId has been added to Cards (as expected/desired), however Sides contains no reference to Stage (not expected).

If I then add

    [Required]
    [ForeignKey("StageId")]
    public virtual Stage Stage { get; set; }
    public int StageId { get; set; }

To my Side class, I see StageId column added to my Side table.

This is working, but now throughout my application, any reference to Stage contains a SideId, which is in some cases totally irrelevant. I'd like to just give my Card and Side entities a Stage property based on the above Stage class without polluting the stage class with reference properties if possible... what am I doing wrong?

The answer is


This sounds weird and I don't know why, but in my case that was happening because my ConnectionString was using "." in "data source" attribute. Once I changed it to "localhost" it workded like a charm. No other change was needed.


public partial class recommended_books : DbMigration
{
    public override void Up()
    {
        CreateTable(
            "dbo.RecommendedBook",
            c => new
                {
                    RecommendedBookID = c.Int(nullable: false, identity: true),
                    CourseID = c.Int(nullable: false),
                    DepartmentID = c.Int(nullable: false),
                    Title = c.String(),
                    Author = c.String(),
                    PublicationDate = c.DateTime(nullable: false),
                })
            .PrimaryKey(t => t.RecommendedBookID)
            .ForeignKey("dbo.Course", t => t.CourseID, cascadeDelete: false) // was true on migration
            .ForeignKey("dbo.Department", t => t.DepartmentID, cascadeDelete: false) // was true on migration
            .Index(t => t.CourseID)
            .Index(t => t.DepartmentID);

    }

    public override void Down()
    {
        DropForeignKey("dbo.RecommendedBook", "DepartmentID", "dbo.Department");
        DropForeignKey("dbo.RecommendedBook", "CourseID", "dbo.Course");
        DropIndex("dbo.RecommendedBook", new[] { "DepartmentID" });
        DropIndex("dbo.RecommendedBook", new[] { "CourseID" });
        DropTable("dbo.RecommendedBook");
    }
}

When your migration fails you are given a couple of options: 'Introducing FOREIGN KEY constraint 'FK_dbo.RecommendedBook_dbo.Department_DepartmentID' on table 'RecommendedBook' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints. Could not create constraint or index. See previous errors.'

Here is an example of using the 'modify other FOREIGN KEY constraints' by setting 'cascadeDelete' to false in the migration file and then run 'update-database'.


I had a table that had a circular relationship with others and i was getting the same error. Turns out it is about the foreign key which was not nullable. If key is not nullable related object must be deleted and circular relations doesnt allow that. So use nullable foreign key.

[ForeignKey("StageId")]
public virtual Stage Stage { get; set; }
public int? StageId { get; set; }

In .NET Core I played with all upper answers - but without any success. I made changes a lot in DB structure and every time added new migration attempting to update-database, but received the same error.

Then I started to remove-migration one by one until Package Manager Console threw me exception:

The migration '20170827183131_***' has already been applied to the database

After that, I added new migration (add-migration) and update-database successfully

So my suggestion would be: clear out all your temp migrations, until your current DB state.


Just for documentation purpose, to someone that comes on the future, this thing can be solved as simple as this, and with this method, you could do a method that disabled one time, and you could access your method normally

Add this method to the context database class:

protected override void OnModelCreating(DbModelBuilder modelBuilder) {
    modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();
}

None of the aforementioned solutions worked for me. What I had to do was use a nullable int (int?) on the foreign key that was not required (or not a not null column key) and then delete some of my migrations.

Start by deleting the migrations, then try the nullable int.

Problem was both a modification and model design. No code change was necessary.


I had this issue also, I solved it instantly with this answer from a similar thread

In my case, I didn't want to delete the dependent record on key deletion. If this is the case in your situation just simply change the Boolean value in the migration to false:

AddForeignKey("dbo.Stories", "StatusId", "dbo.Status", "StatusID", cascadeDelete: false);

Chances are, if you are creating relationships which throw this compiler error but DO want to maintain cascade delete; you have an issue with your relationships.


The existing answers are great I just wanted to add that I ran into this error because of a different reason. I wanted to create an Initial EF migration on an existing DB but I didn't use the -IgnoreChanges flag and applied the Update-Database command on an empty Database (also on the existing fails).

Instead I had to run this command when the current db structure is the current one:

Add-Migration Initial -IgnoreChanges

There is likely a real problem in the db structure but save the world one step at a time...


You can set cascadeDelete to false or true (in your migration Up() method). Depends upon your requirement.

AddForeignKey("dbo.Stories", "StatusId", "dbo.Status", "StatusID", cascadeDelete: false);

I fixed this. When you add the migration, in the Up() method there will be a line like this:

.ForeignKey("dbo.Members", t => t.MemberId, cascadeDelete:True)

If you just delete the cascadeDelete from the end it will work.


I ran into the same problem and stuck for a long. The following steps saved me. Go through the constraints and change the onDelete ReferentialAction to NoAction from Cascade

  constraints: table =>
  {
      table.PrimaryKey("PK_table1", x => x.Id);
      table.ForeignKey(
         name: "FK_table1_table2_table2Id",
         column: x => x.table2Id,
         principalTable: "table2",
         principalColumn: "Id",
         onDelete: ReferentialAction.NoAction);
  });

I was getting this error for lots of entities when I was migrating down from an EF7 model to an EF6 version. I didn't want to have to go through each entity one at a time, so I used:

builder.Conventions.Remove<ManyToManyCascadeDeleteConvention>();
builder.Conventions.Remove<OneToManyCascadeDeleteConvention>();

The simple way is to, Edit your migration file (cascadeDelete: true) into (cascadeDelete: false) then after assign the Update-Database command in your Package Manager Console.if it's problem with your last migration then all right. Otherwise check your earlier migration history, copy those things, paste into your last migration file, after that do it the same thing. it perfectly works for me.


In .NET Core I changed the onDelete option to ReferencialAction.NoAction

         constraints: table =>
            {
                table.PrimaryKey("PK_Schedule", x => x.Id);
                table.ForeignKey(
                    name: "FK_Schedule_Teams_HomeId",
                    column: x => x.HomeId,
                    principalTable: "Teams",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.NoAction);
                table.ForeignKey(
                    name: "FK_Schedule_Teams_VisitorId",
                    column: x => x.VisitorId,
                    principalTable: "Teams",
                    principalColumn: "Id",
                    onDelete: ReferentialAction.NoAction);
            });

Make your Foreign key attributes nullable. That will work.


Anybody wondering how to do it in EF core:

      protected override void OnModelCreating(ModelBuilder modelBuilder)
            {
                foreach (var relationship in modelBuilder.Model.GetEntityTypes().SelectMany(e => e.GetForeignKeys()))
                {
                    relationship.DeleteBehavior = DeleteBehavior.Restrict;
                }
           ..... rest of the code.....

Examples related to .net

You must add a reference to assembly 'netstandard, Version=2.0.0.0 How to use Bootstrap 4 in ASP.NET Core No authenticationScheme was specified, and there was no DefaultChallengeScheme found with default authentification and custom authorization .net Core 2.0 - Package was restored using .NetFramework 4.6.1 instead of target framework .netCore 2.0. The package may not be fully compatible Update .NET web service to use TLS 1.2 EF Core add-migration Build Failed What is the difference between .NET Core and .NET Standard Class Library project types? Visual Studio 2017 - Could not load file or assembly 'System.Runtime, Version=4.1.0.0' or one of its dependencies Nuget connection attempt failed "Unable to load the service index for source" Token based authentication in Web API without any user interface

Examples related to entity-framework

Entity Framework Core: A second operation started on this context before a previous operation completed EF Core add-migration Build Failed Entity Framework Core add unique constraint code-first 'No database provider has been configured for this DbContext' on SignInManager.PasswordSignInAsync The instance of entity type cannot be tracked because another instance of this type with the same key is already being tracked Auto-increment on partial primary key with Entity Framework Core Working with SQL views in Entity Framework Core How can I make my string property nullable? Lazy Loading vs Eager Loading How to add/update child entities when updating a parent entity in EF

Examples related to foreign-keys

Migration: Cannot add foreign key constraint The ALTER TABLE statement conflicted with the FOREIGN KEY constraint Can a foreign key refer to a primary key in the same table? Introducing FOREIGN KEY constraint may cause cycles or multiple cascade paths - why? MySQL Error 1215: Cannot add foreign key constraint MySQL Cannot Add Foreign Key Constraint Delete rows with foreign key in PostgreSQL How to remove constraints from my MySQL table? MySQL - Cannot add or update a child row: a foreign key constraint fails How to remove foreign key constraint in sql server?

Examples related to ef-code-first

EntityType 'IdentityUserLogin' has no key defined. Define the key for this EntityType There is already an object named in the database The entity type <type> is not part of the model for the current context Entity Framework 6 Code first Default value Unique Key constraints for multiple columns in Entity Framework Entity Framework (EF) Code First Cascade Delete for One-to-Zero-or-One relationship Introducing FOREIGN KEY constraint may cause cycles or multiple cascade paths - why? How to delete and recreate from scratch an existing EF Code First database Entity Framework: One Database, Multiple DbContexts. Is this a bad idea? Ignoring a class property in Entity Framework 4.1 Code First

Examples related to entity-framework-4

Entity Framework Join 3 Tables Entity framework self referencing loop detected The object 'DF__*' is dependent on column '*' - Changing int to double LEFT JOIN in LINQ to entities? Introducing FOREIGN KEY constraint may cause cycles or multiple cascade paths - why? The specified type member 'Date' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties How to include a child object's child object in Entity Framework 5 EF Migrations: Rollback last applied migration? The specified type member is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported How to show Alert Message like "successfully Inserted" after inserting to DB using ASp.net MVC3