classes deriving from System.Exception do not serialize/deserialize properly

#In Newtonsoft.Json v11.0.1, without the [Serializable] attribute on MyExceptionClass, the following test fails. Adding it succeeds.

If I run this test with Newtonsoft.Json v10.0.3 it passes without the [Serializable]

    //[Serializable]
   public class MyExceptionClass : Exception
   {
   }

    [Test]
    public void SerializeException()
    {
      Exception exception;
      try
      {
        throw new MyExceptionClass();
      }
      catch (Exception ex)
      {
        exception = ex;
      }
      string sex = JsonConvert.SerializeObject(exception);
      var dex = JsonConvert.DeserializeObject<Exception>(sex);
      Assert.AreEqual(dex.ToString(), exception.ToString());
    }

The error generated is:

System.Runtime.Serialization.SerializationException : Member 'ClassName' was not found.
   at System.Runtime.Serialization.SerializationInfo.GetElement(String name, Type& foundType)
   at System.Runtime.Serialization.SerializationInfo.GetString(String name)
   at System.Exception..ctor(SerializationInfo info, StreamingContext context)
   at Void .ctor(System.Runtime.Serialization.SerializationInfo, System.Runtime.Serialization.StreamingContext)(Object[] )
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateISerializable(JsonReader reader, JsonISerializableContract contract, JsonProperty member, String id)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
   at Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent)
   at Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType)
   at Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type, JsonSerializerSettings settings)
   at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value, JsonSerializerSettings settings)
   at Connexion.Core.Internal.SerializationEx.Deserialize[T](String value) in D:\Development\Bitbucket\connexion\Connexion.Core\Internal\Json\SerializationEx.cs:line 125
   at Connexion.Share.Test.SerializationTests.SerializeException() in D:\Development\Bitbucket\connexion\Connexion.Share.Test\SerializationTests.cs:line 324

[JamesNK]

That’s expected behavior. Json.NET previous wasn’t serializing ISerializable types correctly. The SerializableAttribute is required.

See here for more info https://github.com/dotnet/corefx/issues/23415

[alexhiggins732]

What happens if you don’t have control over the class? For example, .Net Core 2.2 app new System.Exception serializes as:

{
  "Message": "Exception of type 'System.Exception' was thrown.",
  "Data": {},
  "InnerException": null,
  "TargetSite": null,
  "StackTrace": null,
  "HelpLink": null,
  "Source": null,
  "HResult": -2146233088
}

Yet my WebAPI (Net 4.72) using throws the error System.Runtime.Serialization.SerializationException: 'Member 'ClassName' was not found.'.

Serialize a new System.Exception there produces:

{
  "ClassName": "System.Exception",
  "Message": null,
  "Data": null,
  "InnerException": null,
  "HelpURL": null,
  "StackTraceString": null,
  "RemoteStackTraceString": null,
  "RemoteStackIndex": 0,
  "ExceptionMethod": null,
  "HResult": -2146233088,
  "Source": null,
  "WatsonBuckets": null
}

4.7 has System.Exception defined in Assembly = {mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089} where core defines in Assembly = {System.Private.CoreLib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e}

There is no end user control over this.