How to migrate 2.3.2 to 5.0.0

[techpara]

I am currently using 2.3.2 in framework 4.8 but now I am migrating dot net core 9 with iCal.Net 5.0.0. How to upgrade this code? currently it is giving following errror:

"Exception of type 'System.StackOverflowException' was thrown."

void Main()
{
	var calendarHelper = new CalendarHelper();
	var calendarEvent = new CalendarEvent
	{
		ID = 1,
		Start = Convert.ToDateTime("2020-05-01 00:00:00.000"),
		End = Convert.ToDateTime("2020-05-01 00:00:00.000"),
		IsAllDay = true,
		RecurrenceRule = "FREQ=YEARLY;BYDAY=MO,TU,WE,TH,FR;BYMONTH=5;BYSETPOS=1",
		AlertTimespanString = "00.00:00:00"
	};
	TimeSpan interval = TimeSpan.FromMinutes(10);
	var minDateTime = DateTime.Today.Subtract(interval);

	var maxDateTime = DateTime.Today.Add(interval);
	var notificationPeriod = new Period(new CalDateTime(minDateTime), new CalDateTime(maxDateTime));

	var recurrenceDate = calendarHelper.GetRecurrenceDate(calendarEvent, notificationPeriod, true);

	recurrenceDate.Dump();
}
public class CalendarHelper
{
	public DateTime? GetRecurrenceDate(CalendarEvent calendarEvent, IPeriod period, bool useAlertTime = false)
	{
		var iCal = new Calendar();
		var evt = iCal.Create<Event>();
		evt.Start = new CalDateTime(calendarEvent.Start);
		evt.End = new CalDateTime(calendarEvent.End);

		if (calendarEvent.IsAllDay)
		{
			evt.IsAllDay = true;
			var allDayStart = calendarEvent.Start;
			evt.Start = new CalDateTime(allDayStart.Year, allDayStart.Month, allDayStart.Day);
			evt.End = null;
		}

		if (!string.IsNullOrEmpty(calendarEvent.RecurrenceRule))
		{
			evt.RecurrenceRules.Add(new RecurrencePattern(calendarEvent.RecurrenceRule));
		}

		if (!string.IsNullOrEmpty(calendarEvent.RecurrenceException))
		{
			evt.ExceptionDates.Add(new PeriodList(calendarEvent.RecurrenceException.Replace(";", ",").TrimEnd(',')));
		}

		var occurancePeriod = period;
		var alertTime = !string.IsNullOrWhiteSpace(calendarEvent.AlertTimespanString)
			? calendarEvent.Start.Subtract(calendarEvent.AlertTimespan.Value)
			: calendarEvent.Start;

		if (useAlertTime && alertTime != calendarEvent.Start)
		{
			if (alertTime < calendarEvent.Start)
			{
				var diff = calendarEvent.Start - alertTime;
				occurancePeriod = new Period(period.StartTime.Add(diff), period.EndTime.Add(diff));
			}
			else
			{
				var diff = alertTime - calendarEvent.Start;
				occurancePeriod = new Period(period.StartTime.Subtract(diff), period.EndTime.Subtract(diff));
			}
		}

		var occurences = evt.GetOccurrences(occurancePeriod.StartTime, occurancePeriod.EndTime);
		foreach (var occurence in occurences)
		{
			var start = DateUtil.GetSimpleDateTimeData(occurence.Period.StartTime);
			var periodStart = DateUtil.GetSimpleDateTimeData(occurancePeriod.StartTime);

			// fix occurence from before notificationStart
			if (start >= periodStart)
			{
				return start;
			}
		}

		return default;
	}
}

public class CalendarEvent
{
	public int ID { get; set; }

	public string? UserName { get; set; }

	public string? Description { get; set; }

	public DateTime Start { get; set; }

	public string? StartTimezone { get; set; }

	public DateTime End { get; set; }

	public string? EndTimezone { get; set; }

	public bool IsAllDay { get; set; }

	public string? RecurrenceRule { get; set; }

	public string? RecurrenceException { get; set; }

	public TimeSpan? AlertTimespan
	{
		get => string.IsNullOrEmpty(AlertTimespanString) ? default : TimeSpan.Parse(AlertTimespanString);
		set => AlertTimespanString = value?.ToString(@"dd\.hh\:mm\:ss");
	}

	public DateTime? AlertTime { get; set; }

	public string? AlertTimespanString { get; set; }

	public bool Closed { get; set; }

	public string? ClosedBy { get; set; }

	public DateTime? ClosedOn { get; set; }

	public int? LocationID { get; set; }

	public bool Deleted { get; set; }
}

[axunonb]

When coming from v2, the recommendation is to rewrite these few lines of code from scratch.
Looks like part of the code like if (calendarEvent.IsAllDay){...} is redundant anyway.

[techpara]

Can you provide info on which lines to rewrite? any documentation?

[axunonb]

Please have a look at the Wiki for examples, and the unit tests may also be helpful.
Understand, that we don't write the code you need.

[techpara]

I understand that you don't write code for me. But I just use code from your documentation and it gives syntax error.

Reference from where I got code: https://github.com/ical-org/ical.net/wiki/Working-with-recurring-elements

[axunonb]

Examples are updated now for v5

[techpara]

Thanks, I have successfully migrated from 2.3.2 to 5