Не удалось сериализовать тело ответа для типа содержимого

Я создаю приложение MVC4, которое использует как контроллеры, так и ApiControllers. Я изменил маршрут веб-API по умолчанию, чтобы включить имена действий. Когда я пытаюсь получить список тестов, я получаю сообщение об ошибке:

Тип объекта ObjectContent`1 не смог сериализовать тело ответа для тип контента 'application/json; кодировка = UTF-8'

InnerException это (я возвращаю JSON в этом случае, то же самое происходит с XML):

"InnerException": {
"Message": "An error has occurred.",
"ExceptionMessage": "Error getting value from 'IdentityEqualityComparer' on 'NHibernate.Proxy.DefaultLazyInitializer'.",
"ExceptionType": "Newtonsoft.Json.JsonSerializationException",
"StackTrace": " at Newtonsoft.Json.Serialization.DynamicValueProvider.GetValue(Object target) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeISerializable(JsonWriter writer, ISerializable value, JsonISerializableContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeObject(JsonWriter writer, Object value, JsonObjectContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeList(JsonWriter writer, IWrappedCollection values, JsonArrayContract contract, JsonProperty member, JsonContainerContract collectionContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.SerializeValue(JsonWriter writer, Object value, JsonContract valueContract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerProperty) at Newtonsoft.Json.Serialization.JsonSerializerInternalWriter.Serialize(JsonWriter jsonWriter, Object value) at Newtonsoft.Json.JsonSerializer.SerializeInternal(JsonWriter jsonWriter, Object value) at System.Net.Http.Formatting.JsonMediaTypeFormatter.<>c__DisplayClassd.<WriteToStreamAsync>b__c() at System.Threading.Tasks.TaskHelpers.RunSynchronously(Action action, CancellationToken token)",
"InnerException": {
"Message": "An error has occurred.",
"ExceptionMessage": "Common Language Runtime detected an invalid program.",
"ExceptionType": "System.InvalidProgramException",
"StackTrace": " at GetIdentityEqualityComparer(Object ) at Newtonsoft.Json.Serialization.DynamicValueProvider.GetValue(Object target)"
}

Это код, который я запускаю:

// GET api/benchmark/getincomplete
        [HttpGet]
        public IList<Benchmark> GetIncomplete()
        {
            var s = HibernateModule.CurrentSession;
            var benchList = s.QueryOver<Benchmark>()
                                .Where(b => !b.Completed)
                                .Where(b => !b.Deleted)
                                .OrderBy(b => b.Id).Asc
                                .List<Benchmark>();

            return benchList;
        }

И это модель Benchmark:

public class Benchmark
    {
        public virtual int Id { get; set; }
        [Required]
        [DataType(DataType.Date)]
        public virtual DateTime Date { get; set; }
        [Required, ScriptIgnore]
        public virtual IList<TestResult> Results { get; set; }
        [Required]
        public virtual IList<TestCase> TestCases { get; set; }
        [AllowHtml]
        public virtual string Description { get; set; }
        public virtual Device Device { get; set; }        
        public virtual bool Published { get; set; }
        [Display(Name = "Deleted"), ScriptIgnore]
        public virtual bool Deleted { get; set; }
        public virtual bool Completed { get; set; }

        public Benchmark() 
        {
            Results = new List<TestResult>();
            TestCases = new List<TestCase>();
            Published = false;
            Deleted = false;
            Completed = false;
        }
    }

Я не совсем уверен, где проблема. Может ли это быть NHibernate Proxy (я использую Fluent NHibernate)? Странно то, что если я не использую ApiController и не возвращу JSON вручную, это будет отлично!

Update:

В соответствии с приведенным ниже ответом, это код, который я должен был добавить в Application_Start():

HttpConfiguration config = GlobalConfiguration.Configuration;
((DefaultContractResolver)config.Formatters.JsonFormatter.SerializerSettings.ContractResolver).IgnoreSerializableAttribute = true;

Ответы

((DefaultContractResolver)config.Formatters.JsonFormatter.SerializerSettings.ContractResolver).IgnoreSerializableAttribute = true;

  var json = config.Formatters.JsonFormatter;
  json.SerializerSettings.PreserveReferencesHandling=Newtonsoft.Json.PreserveReferencesHandling.Objects;
  config.Formatters.Remove(config.Formatters.XmlFormatter);

public class Store
{

  [StringLength(5)]
    public string Zip5 { get; set; }

    public virtual List<StoreReport> StoreReports { get; set; }  //use a list here
 }

public class Tag
{
public int Id{get;set;}
public string Title{get;set;}
public IList<Location> Locations{get;set;}
}

public class TagResultsViewMapper
{
public int Id{get;set;}
public string Title{get;set;}
//just remove the following relationship 
//public IList<Location> Locations{get;set;}
}