Error with Npgsql

[jigrain]

I use a special package Npgsql to work with PostgreSQL. And I have all models loaded normally except one and the most important one.
Here is the composition of the model:

        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int Id { get; set; }

        public Guid GuidId { get; set; }

        public virtual EventType Type { get; set; }

        public string Title { get; set; }

        public string Desc { get; set; }

        public Guid Author { get; set; }

        public bool IsAllowed { get; set; }

        public DateTime DateStart { get; set; }

        public DateTime DateEnd { get; set; }

        public string Place { get; set; }

        public Guid Responsible { get; set; }

        public DateTime DateCreated { get; set; }

        public DateTime DateUpdated { get; set; }

        public virtual ICollection<EventСomment> Comments { get; set; }

        public virtual ICollection<EventWorker> Workers { get; set; }

        public virtual ICollection<EventAdministration> Administrations { get; set; }

        public virtual ICollection<EventInvitation> invitations { get; set; }

The error I'm getting:
NpgsqlOperationInProgressException: A command is already in progress: SELECT