Asynchronous Action Error (Async)

Question

This action should send an Asynchronous email, all very simple so far, including using the same class in other projects with the same version of MVC. But to my surprise, this project does not run. Simply appears the error below.

Error:

The asynchronous action method 'Forgettingpassword' Returns a Task, which cannot be executed synchronously.

Stacktrace:

at System.Web.Mvc.Async.Taskasyncactiondescriptor.Execute(Controllercontext controllerContext, Idictionary2 parameters) at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary2 Parameters) at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass15.b__12() at System.Web.Mvc.ControllerActionInvoker.Invokeactionmethodfilter(Iactionfilter filter, Actionexecutingcontext preContext, Func`1 continuation) at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass15. <>c__DisplayClass17.b__14() at System.Web.Mvc.ControllerActionInvoker.Invokeactionmethodwithfilters(Controllercontext

Action:

 [AllowAnonymous]
    [HttpPost, ValidateAntiForgeryToken]
    public async Task<ActionResult> EsqueciMinhaSenha(UsuarioEsqueciMinhaSenhaViewModel vModel)
    {
        if (ModelState.IsValid)
        {
            var conteudo = "este é o conteudo do email";
            var nomeDestinatario = "esse é o nome do destinatário";

            if(await EmailService.SendAsync(Language.PasswordRecovery, conteudo, vModel.EmailOuUsername, nomeDestinatario))
            {
                TempData["MensagemRetorno"] = Language.EmailSendedWithSuccess;
                return View("login");
            }
        }

        TempData["MensagemRetorno"] = Language.ErrorSendingEmail;
        return View("EsqueciMinhaSenha");
    }

Sending the e-mail:

public static async Task<bool> SendAsync(string assunto, string conteudo, string destinatario, string nomeDestinatario)
{
    // Habilitar o envio de e-mail
    var appSetting = ConfigurationManager.AppSettings;

    if (appSetting != null && appSetting.Count >= 7 && !string.IsNullOrEmpty(assunto) && !string.IsNullOrEmpty(conteudo) && !string.IsNullOrEmpty(destinatario) && !string.IsNullOrEmpty(nomeDestinatario))
    {
        int port = 0;
        bool useSSl = false;

        using (var msg = new MailMessage
        {
            From = new MailAddress(appSetting["EmailFrom"], appSetting["EmailNameFrom"]),
            Body = WebUtility.HtmlEncode(conteudo)
        })
        {
            int.TryParse(appSetting["EmailPort"], out port);
            bool.TryParse(appSetting["EmailUseSSL"], out useSSl);


            msg.ReplyToList.Add(destinatario);
            msg.To.Add(new MailAddress(destinatario, nomeDestinatario));
            msg.Subject = assunto;
            msg.AlternateViews.Add(AlternateView.CreateAlternateViewFromString(msg.Body, null, MediaTypeNames.Text.Plain));
            msg.AlternateViews.Add(AlternateView.CreateAlternateViewFromString(msg.Body, null, MediaTypeNames.Text.Html));

            using (var smtpClient = new SmtpClient(appSetting["EmailServer"], port))
            {
                var credentials = new NetworkCredential(appSetting["EmailUserName"], appSetting["EmailPassword"]);
                smtpClient.Credentials = credentials;
                smtpClient.EnableSsl = useSSl;
                await smtpClient.SendMailAsync(msg);

                return await Task.FromResult(true);
            }
        }
    }

    return await Task.FromResult(false);
}