Hi, I use Business Calendar Pro on Android. I change one occurrence of a repeating appointment to a different time and now I have a duplicate ID on the DAViCal server: BEGIN:VEVENT CREATED:20140106T230106Z SUMMARY:**** TRANSP:OPAQUE CLASS:PUBLIC DTSTART;TZID=Europe/Berlin:20140226T093000 LOCATION:**** STATUS:CONFIRMED EXDATE:20140312T083000Z EXDATE:20140326T083000Z EXDATE:20140319T083000Z RRULE:FREQ=WEEKLY;WKST=MO;UNTIL=20141224T083000Z DURATION:PT2H30M LAST-MODIFIED:20140320T214312Z DTSTAMP:20140320T214312Z SEQUENCE:3 UID:bkdiwaiy-cmbs-xjpc-pe24-gd16ybt4mfeu END:VEVENT BEGIN:VEVENT DTSTART;TZID=Europe/Berlin:20140402T103000 SUMMARY:**** LOCATION:**** CLASS:PUBLIC TRANSP:OPAQUE STATUS:CONFIRMED DTEND;TZID=Europe/Berlin:20140402T123000 LAST-MODIFIED:20140401T221005Z DTSTAMP:20140401T221005Z SEQUENCE:1 RECURRENCE-ID:20140402T073000Z UID:bkdiwaiy-cmbs-xjpc-pe24-gd16ybt4mfeu END:VEVENT This was the original event: BEGIN:VEVENT CREATED:20140106T230106Z SUMMARY:**** TRANSP:OPAQUE CLASS:PUBLIC DTSTART;TZID=Europe/Berlin:20140226T093000 LOCATION:**** STATUS:CONFIRMED EXDATE:20140312T083000Z EXDATE:20140326T083000Z EXDATE:20140319T083000Z RRULE:FREQ=WEEKLY;WKST=MO;UNTIL=20141224T083000Z DURATION:PT2H30M LAST-MODIFIED:20140320T214312Z DTSTAMP:20140320T214312Z SEQUENCE:3 UID:bkdiwaiy-cmbs-xjpc-pe24-gd16ybt4mfeu END:VEVENT Can I blame this to Business Calendar Pro? -- Johan