Description
The problem
Background
Most iCalendar implementations use some extensions, such as the X-WR-* properties, which are extensively used by Google, Microsoft and others. The most important of these properties is X-WR-TIMEZONE, which is supported and used by Google, Apple, and Microsoft and defines an Olson time zone for "local" events in a calendar.
HomeAssistant currently does not support this time zone definition, and instead mistakenly throws a log error that there is no time zone specified.
Sample data:
BEGIN:VCALENDAR
PRODID:-//myicehockey//NONSGML v1.0//EN
VERSION:2.0
CALSCALE:GREGORIAN
METHOD:PUBLISH
X-WR-CALNAME:MIH Player
X-WR-CALDESC:MIH Player
X-WR-TIMEZONE:Europe/Zurich
BEGIN:VEVENT
ORGANIZER;CN=MIH:MAILTO:app-no-communication@myice.hockey
UID:PP621883
DTSTAMP:20250519T180000Z
CREATED:20250517T073125
LAST-MODIFIED:20250517T073125
DTSTART:20250519T180000
DTEND:20250519T193000
LOCATION:School sports facility, Zurich
SUMMARY:Off-Ice Training
TRANSP:TRANSPARENT
CATEGORIES:PRACTICES
CLASS:PUBLIC
END:VEVENT
BEGIN:VEVENT
ORGANIZER;CN=MIH:MAILTO:app-no-communication@myice.hockey
UID:PP622295
DTSTAMP:20250522T193000Z
CREATED:20250517T073125
LAST-MODIFIED:20250517T073125
DTSTART:20250522T193000
DTEND:20250522T203000
LOCATION:Ice Rink Zurich
SUMMARY:TRAINING
TRANSP:TRANSPARENT
CATEGORIES:PRACTICES
CLASS:PUBLIC
END:VEVENT
This can lead to issues of shifting calendar events when dealing with multiple time zones, e.g. while travelling, see #145087
Solution
- Add support for X-WR-TIMEZONE
Perhaps https://pypi.org/project/x-wr-timezone/ can be of help?
Thoughts
It might also be useful to support X-WR-CALNAME and X-WR-CALDESC properties.
Not sure CATEGORIES is exposed as a property within HomeAssistant - did not get to that yet. But if it isn't that might also be worthwhile as it would be useful for differentiating in rendering and automations.
What version of Home Assistant Core has the issue?
core-2025.5.2
What was the last working version of Home Assistant Core?
No response
What type of installation are you running?
Home Assistant OS
Integration causing the issue
Remote Calendar
Link to integration documentation on our website
https://www.home-assistant.io/integrations/remote_calendar
Diagnostics information
No response
Example YAML snippet
Anything in the logs that might be useful for us?
Logger: homeassistant.components.remote_calendar.ics
Source: components/remote_calendar/ics.py:42
integration: Remote Calendar ([documentation](https://www.home-assistant.io/integrations/remote_calendar), [issues](https://github.com/home-assistant/core/issues?q=is%3Aissue+is%3Aopen+label%3A%22integration%3A+remote_calendar%22))
First occurred: 09:13:58 (1 occurrence)
Last logged: 09:13:58
Error parsing calendar information: Failed to parse calendar TIMEZONE component: At least one standard or daylight definition is requiredAdditional information
No response