global.asax_Application_Error_.cs

protected void Application_Error(object sender, EventArgs e)
{
    // Get the exception object.
    Exception ex = Server.GetLastError();

    // Log the exception and notify system operators
    Logger.GravarLogErro(ex);

    // Em modo debug, deixa estourar a exceção na tela
    CompilationSection compilationSection = (CompilationSection)ConfigurationManager.GetSection(@"system.web/compilation");
    if (!compilationSection.Debug)
    {
        // Clear the error from the server
        Server.ClearError();

        bool isAjaxCall = string.Equals("XMLHttpRequest", Context.Request.Headers["x-requested-with"], StringComparison.OrdinalIgnoreCase);
        if (isAjaxCall)
        {
            Context.Response.ContentType = "application/json";
            Context.Response.StatusCode = 500;
        }
        else
        {
            // Code that runs when an unhandled error occurs
            Server.TransferRequest("~/Erro");
        }
    }
}