ValueError: RRULE UNTIL values must be specified in UTC when DTSTART is timezone-aware

[VPanteleev-S7]

I got this error when parsing a file generated by an Apple product (possibly iCloud).

Here is a reduced calendar file which reproduces the issue:

BEGIN:VCALENDAR
BEGIN:VTIMEZONE
BEGIN:STANDARD
DTSTART:19230916T030000
RRULE:FREQ=YEARLY;UNTIL=19240921T020000Z;BYMONTH=9;BYMONTHDAY=16,17,18,19
TZOFFSETFROM:+0100
TZOFFSETTO:+0000
END:STANDARD
END:VTIMEZONE
END:VCALENDAR

Code to reproduce:

from ics import Calendar
with open("test.ics", "r") as f:
	calendar = Calendar(f.read())

I don't know much about calendar files, but looking at UNTIL=19240921T020000Z, that already looks like UTC to me.

[N-Coder]

I assume this is using ics.py v0.7 as it is probably a problem with arrow, could you retry with v0.8 (from GitHub or the current PyPi Alpha release)?

[VPanteleev-S7]

Still fails after pip install git+https://github.com/ics-py/ics-py, with the same error message.

[N-Coder]

Then this probably also happens when you directly pass this to dateutils ical vtimezone parser? In v0.8 we are no longer wrapping the whole dateutil vtimezone parser, but we still use dateutil functions for working with rrules. So it might be possible to come up with a work-around for this, but I don't yet quite see what is going wrong here (and unfortunately also don't have the time to investigate further). If the same happens with the dateutil ical vtimezone parser, maybe opening an issue there would be the best way to go.