Why does my abstract base class with a generic payload fail to serialize/deserialize correctly with Newtonsoft and System.Text.Json?

I have a service bus event class that inherits from an abstract base class using a generic parameter for its payload, and the base implements an interface. However, no matter what options I try with both Newtonsoft and System.Text.Json, the inner payload isn’t serialized, and deserialization throws an error.

Here’s the problematic code:

CSHARPCopied
private async Task ProcessMessageAsync<T>(ProcessMessageEventArgs args)
{
    try
    {
        var eventTypeInstance = typeof(T);

        var options = new JsonSerializerSettings(){
            ContractResolver = new CamelCasePropertyNamesContractResolver(),
            Converters = new List<Newtonsoft.Json.JsonConverter> { new StringEnumConverter() }
        };

        var body = Encoding.UTF8.GetString(args.Message.Body.ToArray());

        if (eventTypeInstance != null)
        {
            var eventInstance = JsonConvert.DeserializeObject(body, typeof(T), options);
        }
    }
}

The error message:

Newtonsoft.Json.JsonSerializationException: 'Could not create an instance of type ServiceableBus.IServiceableBusPayload. Type is an interface or abstract class and cannot be instantiated. Path 'payload.field1', line 5, position 17.'

Here, <T> is my concrete type.

Below are the relevant class definitions:

CSHARPCopied
public class TestEvent : ServiceableBusEvent<IServiceableBusPayload>
{
    public const string Topic = "test-event";

    public record TestEventPayload(string Field1, int Field2, int Field3) : IServiceableBusPayload;
}

public abstract class ServiceableBusEvent<T> : IServiceableBusEvent where T : IServiceableBusPayload
{
    [JsonPropertyName("messageTypeName")]
    public string MessageTypeName { get; set; }

    [JsonPropertyName("createdAt")]
    public DateTime CreatedAt { get; set; }

    [JsonPropertyName("payload")]
    public T Payload { get; set; }
}

public interface IServiceableBusEvent
{
}

public interface IServiceableBusPayload
{
}

I’m looking for advice on how to ensure the payload is properly serialized and deserialized. Any insight or suggestions for using a concrete type or a custom converter would be appreciated.