.Net 6.0 NotSupportedException: Serialization and deserialization of 'System.Type' instances are not supported

Question

In a .net 6.0 web api application I use smss. When I attempt to run the code I get this Im getting this error when I run the web application:

NotSupportedException: Serialization and deserialization of 'System.Type' instances are not supported. System.Text.Json.Serialization.Converters.UnsupportedTypeConverter.Write(Utf8JsonWriter writer, T value, JsonSerializerOptions options) System.Text.Json.Serialization.JsonConverter.TryWrite(Utf8JsonWriter writer, ref T value, JsonSerializerOptions options, ref WriteStack state) System.Text.Json.Serialization.Metadata.JsonPropertyInfo.GetMemberAndWriteJson(object obj, ref WriteStack state, Utf8JsonWriter writer) System.Text.Json.Serialization.Converters.ObjectDefaultConverter.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, ref WriteStack state) System.Text.Json.Serialization.JsonConverter.TryWrite(Utf8JsonWriter writer, ref T value, JsonSerializerOptions options, ref WriteStack state) System.Text.Json.Serialization.JsonConverter.TryWriteAsObject(Utf8JsonWriter writer, object value, JsonSerializerOptions options, ref WriteStack state) System.Text.Json.Serialization.JsonConverter.TryWrite(Utf8JsonWriter writer, ref T value, JsonSerializerOptions options, ref WriteStack state) System.Text.Json.Serialization.Converters.IEnumerableConverter.OnWriteResume(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, ref WriteStack state) System.Text.Json.Serialization.JsonCollectionConverter<TCollection, TElement>.OnTryWrite(Utf8JsonWriter writer, TCollection value, JsonSerializerOptions options, ref WriteStack state) System.Text.Json.Serialization.JsonConverter.TryWrite(Utf8JsonWriter writer, ref T value, JsonSerializerOptions options, ref WriteStack state) System.Text.Json.Serialization.Metadata.JsonPropertyInfo.GetMemberAndWriteJson(object obj, ref WriteStack state, Utf8JsonWriter writer) System.Text.Json.Serialization.Converters.ObjectDefaultConverter.OnTryWrite(Utf8JsonWriter writer, T value, JsonSerializerOptions options, ref WriteStack state) System.Text.Json.Serialization.JsonConverter.TryWrite(Utf8JsonWriter writer, ref T value, JsonSerializerOptions options, ref WriteStack state) System.Text.Json.Serialization.JsonConverter.WriteCore(Utf8JsonWriter writer, ref T value, JsonSerializerOptions options, ref WriteStack state)

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What should I do to fix this?

using Microsoft.AspNetCore.Mvc;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using System.Data;
using System.Data.SqlClient;
using Microsoft.Extensions.Configuration;
using WebApplication1.Models;


namespace WebApplication1.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class DepartmentController : ControllerBase
    {
        private readonly IConfiguration _configuration;

        public DepartmentController(IConfiguration configuration)
        {
            _configuration = configuration;
        }

        [HttpGet]
        public JsonResult Get()
        {
            string query = @"
                            select DepartmentId, DepartmentName from
                            dbo.Department";
            
            DataTable table = new DataTable();
            string sqlDataSource = _configuration.GetConnectionString("EmployeeAppCon");
            SqlDataReader myReader;
            using(SqlConnection myCon = new SqlConnection(sqlDataSource))
            {
                myCon.Open();
                using(SqlCommand myCommand = new SqlCommand(query, myCon))
                {
                    myReader = myCommand.ExecuteReader();
                    table.Load(myReader);
                    myReader.Close();
                    myCon.Close();
                }
            }
            return new JsonResult(table);
        }
    }
}