using System;

using System.Collections.Generic;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

​

public class Program

{

    public static void Main()

    {

        var errors = new List<string>();

        errors.Add("teste1");

        errors.Add("teste2");

        errors.Add("teste3");

        // Errado

        // var error = JsonConvert.SerializeObject(errors);

        // Certo

        var error = JsonConvert.SerializeObject(errors);

        var resultBody = new Dictionary<string, object>();

        resultBody["error"] = error;

        string resultString = JsonConvert.SerializeObject(resultBody);

        Console.WriteLine(resultString);

        JObject resultObject = JObject.Parse(resultString);

        Console.WriteLine(resultObject);

    }

}