Entity Migration. Could not drop constraint. See previous errors

Here is the code that produce this error. I've tried solution for renaming the AddForeignKey but the error is same.

'PK_dbo.Item' is not a constraint.
Could not drop constraint. See previous errors.

Can you suggest some solution?

public override void Up()
{
    DropForeignKey("dbo.AddGallery", "item_fk_id", "dbo.Item");
    DropForeignKey("dbo.ExtraFieldValue", "item_fk_id", "dbo.Item");
    DropPrimaryKey("dbo.Item");
    AddColumn("dbo.Item", "id", c => c.Int(nullable: false, identity: true));
    AddPrimaryKey("dbo.Item", "id");
    AddForeignKey("dbo.AddGallery", "item_fk_id", "dbo.Item", "id");
    AddForeignKey("dbo.ExtraFieldValue", "item_fk_id", "dbo.Item", "id");
    DropColumn("dbo.Item", "item_id");
}

public override void Down()
{
    AddColumn("dbo.Item", "item_id", c => c.Int(nullable: false, identity: true));
    DropForeignKey("dbo.ExtraFieldValue", "item_fk_id", "dbo.Item");
    DropForeignKey("dbo.AddGallery", "item_fk_id", "dbo.Item");
    DropPrimaryKey("dbo.Item");
    DropColumn("dbo.Item", "id");
    AddPrimaryKey("dbo.Item", "item_id");
    AddForeignKey("dbo.ExtraFieldValue", "item_fk_id", "dbo.Item", "id");
    AddForeignKey("dbo.AddGallery", "item_fk_id", "dbo.Item", "id");
}