Problems with routes in ASP.NET MVC

Hello, I have the following route:

routes.MapRoute("RelatorioDemonstrativoResultadoExercicio", "downloads/relatorios/Relatorio_DRE_{dataInicio}_{dataTermino}.pdf", new { controller = "RelatorioFinanceiro", action = "DemonstrativoResultadoExercicio" }); 

Use it to create a PDF and download it to the client. The problem is that it has stopped working. I updated the MVC and just stopped.
It no longer locates the controller or anything. However, if I do this:

routes.MapRoute("RelatorioDemonstrativoResultadoExercicio", "downloads/relatorios/Relatorio_DRE/{dataInicio}/{dataTermino}", new { controller = "RelatorioFinanceiro", action = "DemonstrativoResultadoExercicio" });

It works again. Does anyone know what happened? What should I do to make my old route work?
Here is the Controller that should be triggered:

public void DemonstrativoResultadoExercicio(DateTime dataInicio, DateTime dataTermino)
    {
        dataInicio = dataInicio.Date;
        dataTermino = new DateTime(dataTermino.Year, dataTermino.Month, dataTermino.Day, 23, 59, 59);

        BancoDadosBO db = new BancoDadosBO();
        RelatorioFinanceiroCO.DemonstrativoResultadoExercicio(Response.OutputStream, db, idContaSistema, idUsuario, dataInicio, dataTermino);
        db.Commit();

        Response.ContentType = "application/pdf";
        Response.AddHeader("Content-Disposition", "attachment");
        Response.End();
    }