Calendar shows events exported from Thunderbird in a wrong timezone

[mdindoffer]

Distribution

Mint 21.2

Package version

5.8.4

Graphics hardware in use

No response

Frequency

Always

Bug description

The (Gnome) calendar applet is showing events in a wrong timezone - as if they were specified in UTC and then applies the conversion to local TZ. For example, events scheduled at 9:30 are shown as occurring at 11:30 due desktop using CEST.

The same applies for the Gnome Calendar app (41.2) view:

Steps to reproduce

• Set up synchronization of calendar in Thunderbird with Gnome Calendar
• Enable "Show calendar events" in the Calendar Applet configuration
• Accept an invitation to an event in Thunderbird

Expected behavior

The times should be the same, no TZ conversion should take place.

Additional information

• Thunderbird 115.3.1 from Cinnamon repo
• Gnome Calendar app 41.2+mint1+vanessa from Cinnamon repo

I found Gnome bugreports such as this one, mentioning this exact problem. Maybe Cinnamon is just missing backports of some of the fixes?

[mtwebster]

I can't reproduce this. I'm using the 'EDS Calendar Integration' plugin in Thunderbird (not sure if there are others).

Looking at a couple of commits linked in that bug report:

https://gitlab.gnome.org/GNOME/gnome-calendar/-/commit/bde989cc0ef493ab42e53b13af0a592110500c88 - this works around libical < 3.0.12, but we have 3.0.14.

'https://gitlab.gnome.org/GNOME/gnome-calendar/-/commit/be95d58cda074d5efaf5500158a3e276a2349ba5 - this is one we don't have.

We can look at backporting some fixes, but I need to be able to reproduce the issue. Is this a new installation/setup? Or did it work in the past? I'm assuming your locale (cinnamon settings -> Date & Time) are correct. Have you tried removing/reconnecting the calendar and plugin?

The only timezone-related issue I've ever noticed with the calendar is that evolution popup reminders can be an hour off (presumably due to daylight savings), but that's a bug in evolution as far as I know - they show up correctly in the calendar applet and gnome-calendar.

[mdindoffer]

I'm using the 'EDS Calendar Integration' plugin in Thunderbird (not sure if there are others).

Yes, that's the one I'm using as well.

Is this a new installation/setup? Or did it work in the past?

No, this is an upgraded system, fresh install was Mint 21.1. Yes, it did work in the past correctly, the problem started happening fairly recently (sometime within the last ~3 weeks or so). The only relevant thing that I updated in that time is Thunderbird as far as I can tell. Here's my /var/log/apt/history.log for that period: history.log

I'm assuming your locale (cinnamon settings -> Date & Time) are correct.

Yes, system TZ is set correctly.

Have you tried removing/reconnecting the calendar and plugin?

Not yet, but I will try and let you know shortly.

[mdindoffer]

Have you tried removing/reconnecting the calendar and plugin?

Adding and removing the calendar in Gnome Calendar app (and re-synchronizing) did not help. Similarly, disabling the EDS Thunderbird plugin and re-enabling it did not help. I also tried combining these steps and restarting Thunderbird and the Gnome App in between.

[mdindoffer]

This is still causing problems:

Is there anything else I can do to help debug this? Any other useful logs?

[mtwebster]

Go into Thunderbird's settings (edit->settings), then scroll all the way to the bottom and click "Config Editor"..

In there, type calendar.timezone - check the locale there. You can try resetting those keys (trashcan at the end of the row), then restart Thunderbird. The useSystemTimezone should be set to true, which would make it follow whatever location you have set in Cinnamon's Date/Time settings.

[mdindoffer]

It says Prague/Europe (which is OK) and calendar.timezone.useSystemTimezone is set to true. Tried deleting with the ThrashCan icon, restarted Thunderbird, but the bug persists:

What I found out though, is that the time is correct if I simply create an event in my local Thunderbird Calendar directly. But the time is wrong, whenever I accept an e-mail invitation to an event from someone else and it gets added to my calendar.

[irm-codebase]

@mtwebster I am experiencing the same +2 shift when adding a calendar through .ics

Here is an example of the Cinnamon calendar (left) vs Outlook web (right). Same issue (@mdindoffer is in the same timezone as me).

I removed the default calendar app in Cinnamon (41.2+mint) and installed the Flatpack (45.0) and items were displayed correctly, but unfortunately desktop applet support did not work.

Seems like this behaviour is caused by GNOME calendar itself. See the following: issue 1, issue 2, and issue 3. Looks like UTC timezone support is kind of shoddy. Upgrading the version used by Cinnamon might still solve our particular case of this problem though.

[mdindoffer]

@mtwebster Any success reproducing it? I still didn't pinpoint the problem, but what might help you reproduce is to create an event in MS Outlook or smth similar, and then send yourself an invite via email. Accept in Thunderbird and there you go, timezone is off.

Alternatively, importing an ics file could work, as reported by @irm-codebase.

[irm-codebase]

I would recommend updating the GNOME version used by Cinnamon. It seems to fix this issue.