Hello,
I’m using eM Client 11.0.865 on Windows with a CalDAV account on an IServ server (DAViCal 1.1.12). On my Android phone, I sync the same task list using DAVx⁵ and Tasks.org.
When I mark a single occurrence of a recurring task as completed in eM Client, eM Client creates an exception with a RECURRENCE-ID. However, its value type does not match the start date of the series. Excerpt from “Show as iCalendar”:
Series:
DTSTART;TZID=W. Europe Standard Time:20261002T000000
DUE;TZID=W. Europe Standard Time:20261002T235959
RRULE:FREQ=WEEKLY;INTERVAL=2;BYDAY=FR
Exception (completed occurrence):
RECURRENCE-ID;VALUE=DATE:20261002
STATUS:COMPLETED
The series has a DTSTART of type DATE-TIME with a time zone, whereas the RECURRENCE-ID is a plain date (VALUE=DATE). According to RFC 5545, section 3.8.4.4, the RECURRENCE-ID must have the same value type as the DTSTART of the series. The correct form here would be:
RECURRENCE-ID;TZID=W. Europe Standard Time:20261002T000000
As a result, other clients cannot match the exception to any occurrence. In eM Client, the occurrence is marked as completed and the next due date is shown, while on all other devices the task remains open with the old date.
Could you please look into this and fix it?
Best regards,
Philipp Wehmann