Entity Framework .net: "The Name value should be a valid navigation property name."

Ok. I've solved this issue. Just in case anyone have the same problem, here is the problem and the answer:

I had my entities like:

namespace PlataformaTest.Models{    public class AnswerModel    {        public int Id { get; set; }        public string UserId { get; set; }        [ForeignKey("OptionModel"), Column(Order = 0)]        public int QuestionId { get; set; }        [ForeignKey("OptionModel"), Column(Order = 1)]        public int OptionId { get; set; }        [JsonIgnore]        public virtual OptionModel OptionModelEx { get; set; }    }}

But I found out, that

ForeignKey("OptionModel") 

has to have the same name of the "Virtual" variable. Like this:

namespace PlataformaTest.Models{    public class AnswerModel    {        public int Id { get; set; }        public string UserId { get; set; }        [ForeignKey("OptionModel"), Column(Order = 0)]        public int QuestionId { get; set; }        [ForeignKey("OptionModel"), Column(Order = 1)]        public int OptionId { get; set; }        [JsonIgnore]        public virtual OptionModel OptionModel { get; set; }    }}

I thought it had to have the name of the Class, but it doesn't. It looks for the name of the object to map the Entity's Foreign Key.