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ICS calendar off by an hour

Entropie
Copper Contributor

‎May 05 2022 03:58 AM - edited ‎May 05 2022 07:15 AM

‎May 05 2022 03:58 AM - edited ‎May 05 2022 07:15 AM

ICS calendar off by an hour

Hi,

I wish to summit a bug issue about calendar events that are one hour off, that happens to my clients as well as my collègues on OS Windows 10 Pro 21h1 Build 19044.1288 and Windows 11 Pro 21h2 Build 22000.613 and Office 365 accounts.

 

I generate an ICS file :

BEGIN:VCALENDAR
PRODID:-//Stilog IST//VP ICAL//EN
VERSION:2.0
CALSCALE:GREGORIAN
METHOD:PUBLISH
X-WR-CALNAME:Mes activités du jour - Pôle Relation Client
BEGIN:VEVENT
DTSTAMP:20220504T134301Z
UID:A2C7-7DE4-FEED-E7E1-BE96-8157-25FD-A33A
SUMMARY: REQUETES (File conducteurs)\nSWITCH (Switch)\nTELEPHONE (C
hoix 5 Conducteurs)
DESCRIPTION:Ci-dessous vos activités du jour:\n\n 08:30-16:30 | REQUETES
- File conducteurs\n 08:30-16:30 | SWITCH - Switch\n 08:30-16:30 | TELEP
HONE - Choix 5 Conducteurs\nLocalisation: Sur site\n
DTSTART;TZID=Europe/Paris:20220502T083000
DTEND;TZID=Europe/Paris:20220502T163000
TRANSP:OPAQUE
END:VEVENT

 

We can see that the intended hours in purple matches the lines in red, yet when i import the planning, i witness the event (and every other events imported, i use this one as an example) is an hour off.

 

 

Entropie_0-1651748259287.png

 

 Same behaviour on Thunderbird :

Entropie_1-1651748259292.png

 

 

I didn’t experienced this behaviour when using an API to synchronise the calendar directly from Microsoft Azure, the hours are correct in Windows 11 and 10 :

 

 

Windows 11

Entropie_2-1651748259297.png

 

 

 

Windows 10

Entropie_3-1651748259315.png

 

 

 

 

 

I tested changing the UTC and these are the results i found :

- (In Windows 11) I disabled the summer hour and changed the UTC from (UTC+01:00) Bruxelles, Copenhague, Madrid, Paris to (UTC+01:00) Belgrade, Bratislava, Budapest, Ljubljana, Prague, And my events got back to the intended hours, but on windows the hour isn’t correct anymore, yet the hour showed is correct.

Entropie_4-1651748259319.png

 

Entropie_5-1651748259325.png

 

- (In Windows 10) I disabled the summer hour in windows and in option -> calendar -> changed the UTC from (UTC+01:00) Bruxelles, Copenhague, Madrid, Paris to (UTC+01:00) Belgrade, Bratislava, Budapest, Ljubljana, Prague, But the behaviour is different from Windows 11 in the sense that the hour displayed and system is the same

Entropie_6-1651748259340.png

 

Entropie_7-1651748259341.png

 

If i activate the summer hour i get the hour off again but the hour displayed by windows in correct.

Entropie_8-1651748259345.png

 

If someone has an idea, for me it's a problem on Microsoft's end, but i might be wrong, it doesn’t makes sense since the .ics file is correct and the timezone generated as well as the one from the Calendar is the same.

Thanks for anyone who can assist.

 

 

 

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Entropie

‎May 09 2022 08:10 AM - edited ‎May 09 2022 08:29 AM

‎May 09 2022 08:10 AM - edited ‎May 09 2022 08:29 AM

Re: ICS calendar off by an hour

I was able to retrieve the normal hours by modifying the .ics file with this part, right before "begin:vevent"


BEGIN:VTIMEZONE
TZID:Europe/Paris
    BEGIN:STANDARD
        DTSTART:20220101T00000
        RRULE:FREQ=YEARLY;BYDAY=1SU;BYMONTH=11
        TZOFFSETFROM:+0200
        TZOFFSETTO:+0200
    END:STANDARD
    BEGIN:DAYLIGHT
        DTSTART:20220101T000000
        RRULE:FREQ=YEARLY;BYDAY=2SU;BYMONTH=3
        TZOFFSETFROM:+0200
        TZOFFSETTO:+0200
    END:DAYLIGHT
END:VTIMEZONE

We didn't experienced this behaviour before, and have been using it for six years already, did Microsoft changed the way time zones have to be coded ?

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