Bypassing notfound error with System Xelement

Question

void SaveKurByDayAsync(DateTime firstDay , DateTime lastDay)
{
    List<DateTime> dateList = new();

    for (DateTime date = firstDay; date <= lastDay; date = date.AddDays(1))
    {
        dateList.Add(date); 
    }

    foreach (DateTime date in dateList)
    {
        string day = date.Day.ToString();
        string year = date.Year.ToString();
        string month = date.Month.ToString();

        if (int.Parse(month) < 10)
            month = "0" + month;

        if (int.Parse(day) < 10)
            day = "0" + day;

        string format = null;
        if (date == DateTime.Today)
            format = "https://www.tcmb.gov.tr/kurlar/today.xml";


        format = "https://www.tcmb.gov.tr/kurlar/" + year + month + "/" + day + month + year + ".xml";

        List<XElement> exchangeList = XElement.Load(format).Elements().ToList();

        foreach (XElement exchangeItem in exchangeList)
        {

            Console.WriteLine(decimal.Parse(exchangeItem.Element("ForexBuying").Value, NumberStyles.Number, CultureInfo.InvariantCulture));
        }


    }
}

I have a method that gets exchange rate information published in xml format every day. But on public holidays xml is not published here and I get NotFound error in 'Load' method. I want to skip that day and move on to the next day, but I couldn't figure it out.