Bug 412025 - Wrong timezone offset with TZID=Western/Central Europe
Summary: Wrong timezone offset with TZID=Western/Central Europe
Alias: None
Product: frameworks-kcalendarcore
Classification: Frameworks and Libraries
Component: general (show other bugs)
Version: 5.9.0
Platform: Ubuntu Linux
: NOR normal
Target Milestone: ---
Assignee: kdepim bugs
Depends on:
Reported: 2019-09-18 15:26 UTC by Roland Tapken
Modified: 2021-07-01 16:01 UTC (History)
2 users (show)

See Also:
Latest Commit:
Version Fixed In:

Invitation from the web client (1.26 KB, text/calendar)
2019-09-18 15:26 UTC, Roland Tapken
Invitation from the desktop client (1.26 KB, text/calendar)
2019-09-18 15:26 UTC, Roland Tapken
Translate wrong TZID into correct one (600 bytes, patch)
2019-09-19 11:24 UTC, Roland Tapken
compare import of c165914.ics and c165915.ics (50.96 KB, image/png)
2019-11-30 15:18 UTC, Allen Winter
Another example of an nearly missed invitation (809 bytes, text/calendar)
2021-07-01 15:52 UTC, Roland Tapken

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Description Roland Tapken 2019-09-18 15:26:33 UTC
Created attachment 122706 [details]
Invitation from the web client


Whenever I get an invitation from someone using IBM Notes' Webclient Korganzizer calculates a wrong timezone offset. The attached invitation c165914.ics get's imported with a start time of 13:00 CEST, while c165915.ics (generated by Notes' desktop application) is correctly imported as 12:00 CEST.

I analyzed the differences between these file, and the only relevant difference is the TZID. While "TZID:W. Europe Standard Time" (desktop application) is handled correctly by Korganizer, "TZID:Western/Central Europe" (web client) is imported with a +1 offset.

A assume that the real problem is that one of these TZIDs generated by Lotus Notes is wrong, but I'm also sure that IBM will never fix this problem. So maybe it can be work around in the clients.

1. Send an invitation with Notes Webclient
2. Import with Korganizer


Come one hour late to the appointment (happened multiple times to me).


Be in time.

Linux/KDE Plasma
KDE Plasma Version: 18.12.3
KDE Frameworks Version: 5.56.1
Qt Version: 5.12.2
Comment 1 Roland Tapken 2019-09-18 15:26:53 UTC
Created attachment 122707 [details]
Invitation from the desktop client
Comment 2 Roland Tapken 2019-09-19 11:24:43 UTC
Created attachment 122720 [details]
Translate wrong TZID into correct one

I've written a proof-of-concept patch for kcalcore that translates the wrong TZID into a correct one. However, I think that here is a general decision is necessary if and how to deal with false TZIDs in invitations of other clients.
Comment 3 Allen Winter 2019-10-14 21:20:03 UTC
I'm happy to see your proof-of-concent workaround.
Comment 4 Allen Winter 2019-11-30 15:17:58 UTC
Roland, I tested in KOrganizer 19.11 with modern libical v3.0.6 and the import seems to work fine.  I imported both c165914.ics and c165915.ics 
see the screenshot with side-by-side summaries
Comment 5 Allen Winter 2019-11-30 15:18:40 UTC
Created attachment 124211 [details]
compare import of c165914.ics and c165915.ics
Comment 6 Roland Tapken 2019-12-05 15:42:55 UTC
Allen, I wrote the bug report on October 14th, in Daylight Saving Time (CEST). Can you change your system date to summer and check again? Ubuntu still delivery libical 3.0.5, so I cannot test directly.
Comment 7 Roland Tapken 2019-12-05 15:45:04 UTC
Correction: I wrote it on September 18th, your first comment was from October. But still in DST, which might matter regarding a 1-hour-offset.
Comment 8 Roland Tapken 2019-12-05 15:53:49 UTC
I've checked the diff from 3.0.5 to 3.0.6, it might be possible that the problem has really been solved since the new version contains new code to parse TZOFFSETFROM and TZOFFSETTO, which might resolve the issue.

I'll try to backport the patch to 3.0.5 and update my Ubuntu package.
Comment 9 Ahmad Samir 2021-06-13 09:59:43 UTC
Closing, per comment 7.
Comment 10 Roland Tapken 2021-06-13 14:43:04 UTC
(In reply to Ahmad Samir from comment #9)
> Closing, per comment 7.

Sorry, the problem has not been fixed, imports from Notes with TZ "Western/Central Europe" are still not assigned to the correct time zone. I've still applying my patch from comment #2 to every new release to fix the problem for me. I just forgot to provide feedback.
Comment 11 Roland Tapken 2021-06-13 14:56:49 UTC
(In reply to Ahmad Samir from comment #9)
> Closing, per comment 7.

Sorry, is seems that you were right, I was so used to apply this patch that I didn't even recognized that the problem has been fixed. I couldn't reproduce the problem with the original version from repo. Please close again.
Comment 12 Roland Tapken 2021-07-01 15:50:09 UTC
The problem still exists, I nearly missed an appointment because of it.

I'll attach the anonymized invitation I've received yesterday, which was imported as "2021-07-02 14:00" (UTC+1) by Korganizer but really is "2021-07-02 13:00" (CEST).

The reason still seems to be the wrong TZID "Western/Central Europe" used by the Notes Calender web client.
Comment 13 Roland Tapken 2021-07-01 15:52:09 UTC
Created attachment 139786 [details]
Another example of an nearly missed invitation
Comment 14 Roland Tapken 2021-07-01 16:01:27 UTC
Please note that my suggested patch from comment #2 still works perfectly to resolve this issue. Just merge it into tree and this bug can be closed :-)