Entity Framework code-first approach error: sequence contains more than one element , for table with foreign key

Question

I am using EF with a code-first approach. I have two model classes:

public class Terminal
{
    public Terminal()
    {
        Softwares = new List<Software>();
    }

    public Guid Id { get; set; }

    public ICollection<Software> Softwares { get; set; }
}

This software class has a foreign key to the Terminal table:

public class Software
{
    public Guid Id { get; set; }
    public string Name { get; set; }

    public Guid TerminalId { get; set; }

    public virtual Terminal Terminal { get; set; }
}

Creating the migration with the command add-migration "add foreign key " works fine. However when I call the update-database command from the package manager console, I get this error:

System.InvalidOperationException: Sequence contains more than one element
at System.Linq.Enumerable.SingleOrDefault[TSource](IEnumerable1 source)
at System.Data.Entity.Migrations.DbMigrator.FillInForeignKeyOperations(IEnumerable1 operations, XDocument targetModel)
at System.Data.Entity.Migrations.DbMigrator.ExecuteOperations(String migrationId, VersionedModel targetModel, IEnumerable1 operations, IEnumerable1 systemOperations, Boolean downgrading, Boolean auto)
at System.Data.Entity.Migrations.DbMigrator.ApplyMigration(DbMigration migration, DbMigration lastMigration)
at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.ApplyMigration(DbMigration migration, DbMigration lastMigration)
at System.Data.Entity.Migrations.DbMigrator.Upgrade(IEnumerable1 pendingMigrations, String targetMigrationId, String lastMigrationId)
at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.Upgrade(IEnumerable1 pendingMigrations, String targetMigrationId, String lastMigrationId)
at System.Data.Entity.Migrations.DbMigrator.UpdateInternal(String targetMigration)
at System.Data.Entity.Migrations.DbMigrator.<>c__DisplayClassc.b__b()
at System.Data.Entity.Migrations.DbMigrator.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
at System.Data.Entity.Migrations.Infrastructure.MigratorBase.EnsureDatabaseExists(Action mustSucceedToKeepDatabase)
at System.Data.Entity.Migrations.DbMigrator.Update(String targetMigration)
at System.Data.Entity.Migrations.Infrastructure.MigratorBase.Update(String targetMigration)
at System.Data.Entity.Migrations.Design.ToolingFacade.UpdateRunner.Run()
at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
at System.Data.Entity.Migrations.Design.ToolingFacade.Run(BaseRunner runner)
at System.Data.Entity.Migrations.Design.ToolingFacade.Update(String targetMigration, Boolean force)
at System.Data.Entity.Migrations.UpdateDatabaseCommand.<>c__DisplayClass2.<.ctor>b__0()
at System.Data.Entity.Migrations.MigrationsDomainCommand.Execute(Action command)
Sequence contains more than one element

I have updated the EF as well from the console

This works fine in my environment. Maybe you have other pending migrations or changes? — illug

illug illug · Accepted Answer · 2017-03-20T13:30:00

I would assume that you are using SingleOrDefault in your seed method, same as in this thred:

InvalidOperationException: Sequence contains more than one element

Entity Framework code-first approach error: sequence contains more than one element , for table with foreign key

1 Answers