Dear community, My weekly routine involves adding descriptions to recurring events. Before migrating to Thunderbird/Lightning (Remote Calendar via CalDAV hosting provider) from Outlook (Remote Calendar via Exchange/Office Enterprise), it was the easiest and quickest way to have detailed recurring events: The meeting itself is recurring, and always at the same location, just every week I add a description. The modified event itself was not part of the recurrence anymore, but that was fine. Now, in Thunderbird, I run into this problem: If I have a recurrent event (with time and location set) and modify a single occurrence (adding a description), the modified occurrence will have "forgotten" its location. Even worse, while the editing dialog is still open, it will show the location, but when I then save and close it, the location is gone (both in the calendar view, and when I open it again). The problem is appearing using both Lightning CalDAV as well as TbSync CalDAV. If I change the description and the location for a single occurrence, it remembers both correctly. If I use my web-based CalDAV interface from the hosting provider, editing a single occurrence keeps the location, and it also syncs back correctly to Thunderbird. I have tried the same for local calendars and the problem is not appearing in this case. Editing a single event keeps the location information correctly in Thunderbird 60.9.1 (32-bit) / Lightning 6.2.9.1. If I export the local test calendar, which only includes the series as well as the modified event (and appears correctly in Lightning), the .ics file (attached below) does not contain the location information in the modified VEVENT. Importing it (even to another, local test calendar) also does not reload the location from the reoccurring event. I really want to stay with CalDAV and Thunderbird, but this is really annoying. I have a couple of questions therefore on how to mitigate or understand this: 1. What is the expected behavior in the CalDAV standard, especially concerning the import/export function? 2. Is this the expected Lightning behavior ("forgetting" the location from the recurring event, even though showing it in the editing dialog initially)? 3. Is the import/export problem related to how Lightning/TbSync talk to the CalDAV-server, making the same problem appear in remote calendars? Edit: I reported the bugs: https://bugzilla.mozilla.org/show_bug.cgi?id=1595332 and https://bugzilla.mozilla.org/show_bug.cgi?id=1595334 Cheers, PBB ========================================================= These are my software versions, although this problem has been persisted for a month: Thunderbird Version: 68.2.1 (32-bit) Lightning Version: 68.2.0 TbSync Version: 2.7 ========================================================= BEGIN:VCALENDAR PRODID:-//Mozilla.org/NONSGML Mozilla Calendar V1.1//EN VERSION:2.0 BEGIN:VTIMEZONE TZID:America/Los_Angeles BEGIN:DAYLIGHT TZOFFSETFROM:-0800 TZOFFSETTO:-0700 TZNAME:PDT DTSTART:19700308T020000 RRULE:FREQ=YEARLY;BYDAY=2SU;BYMONTH=3 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:-0700 TZOFFSETTO:-0800 TZNAME:PST DTSTART:19701101T020000 RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=11 END:STANDARD END:VTIMEZONE BEGIN:VEVENT CREATED:20191105T225831Z LAST-MODIFIED:20191105T225906Z DTSTAMP:20191105T225906Z UID:fa7cf9e3-9a58-495f-8286-f8bd0e3fc40c SUMMARY:Test-Recurrence RRULE:FREQ=DAILY;UNTIL=20191108T161500Z DTSTART;TZID=America/Los_Angeles:20191104T081500 DTEND;TZID=America/Los_Angeles:20191104T091500 TRANSP:OPAQUE LOCATION:My Room X-MOZ-GENERATION:1 END:VEVENT BEGIN:VEVENT CREATED:20191105T225854Z LAST-MODIFIED:20191105T225906Z DTSTAMP:20191105T225906Z UID:fa7cf9e3-9a58-495f-8286-f8bd0e3fc40c SUMMARY:Test-Recurrence RECURRENCE-ID;TZID=America/Los_Angeles:20191105T081500 DTSTART;TZID=America/Los_Angeles:20191105T081500 DTEND;TZID=America/Los_Angeles:20191105T091500 DESCRIPTION:Description TRANSP:OPAQUE CLASS: END:VEVENT END:VCALENDAR =========================================================