ICalendar and event updates not working in Outlook

Question

I\'m generating ICalendar (.ics) files.

Using the UID and SEQUENCE fields I can update existing events in Google Calendar and in Windows Calendar BUT NOT

Answer 1

add this to your ICS file

X-WR-RELCALID:MyCal123   

where MyCal123 is a unique identifier for your calendar.

By adding this line to an ICS file the entire calendar gets updated (after a prompt in Outlook). You don't even need to change the DTSTAMP or SEQUENCE or ORGANIZER and METHOD:PUBLISH is fine for the update. Just update the event details, double-click the ICS and the calendar will update. Note that this also works fine if you have published the calendar and provided a URL for people to view it. They just need to hit refresh after about 2mins and they will also get the update.

Thanks to David Bjørnhart for pointing this out: ICal import creates new calendar When Open the ics file