Thanks for your kind advice. I have opened an issue on the nextcloud github page:
Timezone issues leading to double-booked appointments
I looked for timezone in the FAQ and configuration pages and didn’t find it discussed there.
- DAViCal server on Debian jessie, v126.96.36.199-1
- Mozilla Lightning / Iceowl on Debian v31.8.0-1~deb8u1
- DAVDroid from fdroid, v0.8.1
- Cyanogenmod Calendar app version 4.4.4-9329c12b93
- both the desktop computer and the phone are configured for Central European Summer Time (CEST, UTC+2)
I’ve observed the following problem with duplicate appointments due to timezone confusion:
on the computer create an appointment at 14:00 on 1 October 2015. In Iceowl, I click “Options” and “Show Timezones” and it is showing “Europe/Zurich”
look at the appointment in the calendar on the phone, it appears at 15:00 on 1 October 2015 and CEST is mentioned. If I click to edit on the phone, I also see “Central European Summer Time GMT+2”
create an appointment in the phone for 14:00 on 1 October 2015. In the editing form, it also shows “Central European Summer Time GMT+2” but in the read-only view it doesn’t mention the time zone at all.
look on the computer, both appointments appear at 14:00 on 1 October 2015, expecting me to be in two places at the same time. The appointment created on the phone in step (3) appears as “Europe/Amsterdam” timezone
Are there known problems with timezones, either in DAVdroid or the Calendar app?
Should I troubleshoot this further or is somebody already working on it?
No, these problems are not known and timezones should work. However, there was a bug in recent DAVdroid versions – please use the latest version (after installing it, please add the accounts again to ensure everything is correctly synced) to debug this.
The latest version currently is 0.8.4.1
I looked at some of the other appointments in the calendar and I noticed they were correct. It is only the appointment on 1 October 2015 that has the problem.
I am going to try re-installing DAVdroid and see what happens.
I installed 0.8.4.1 and looked at the calendar and it was still wrong
I created two more appointments on that day, one created by the Mozilla on my workstation, the other created using the calendar. Both of them appeared at correct times.
Then I removed the account from DAVdroid and created the account again. Looking at the calendar after this, I found that both 14:00 appointments now appear at 14:00.
Yes, after installing 0.8.4.1, you have to create the account again because events that are already synced (with the wrong date) are not synced again until they change (only updated events are fetched at a sync).