Couldn't parse iCalendar

[graue70]

This file leads to the error:

BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Something//Calendar//DE
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VTIMEZONE
TZID:Europe/Berlin
BEGIN:STANDARD
DTSTART:20241027T010000
TZOFFSETTO:+0100
TZOFFSETFROM:+0200
RRULE:FREQ=YEARLY;BYMONTH=11;BYDAY=1SU
END:STANDARD
BEGIN:DAYLIGHT
DTSTART:20240331T010000
TZOFFSETTO:+0200
TZOFFSETFROM:+0100
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=2SU
END:DAYLIGHT
END:VTIMEZONE
BEGIN:VEVENT
UID:[email protected]
DTSTART:20240123T153000
DTEND:20240123T170000
SUMMARY:Test
DESCRIPTION:Test
<br>Test-Test\;
DTSTAMP:20240116T201402Z
END:VEVENT
END:VCALENDAR

The error comes from the event description.
The validator at https://icalendar.org/validator.html says that the file is fine.

Stacktrace:

Couldn't parse iCalendar

at.bitfire.ical4android.InvalidCalendarException: Couldn't parse iCalendar
	at at.bitfire.ical4android.ICalendar$Companion.fromReader(ICalendar.kt:91)
	at at.bitfire.ical4android.Event$Companion.eventsFromReader(Event.kt:79)
	at at.bitfire.ical4android.Event$Companion.eventsFromReader$default(Event.kt:78)
	at at.bitfire.icsdroid.ProcessEventsTask$processEvents$downloader$1.onSuccess(ProcessEventsTask.kt:121)
	at at.bitfire.icsdroid.CalendarFetcher.fetchNetwork$icsx5_72_2_1_1_standardRelease(CalendarFetcher.kt:157)
	at at.bitfire.icsdroid.CalendarFetcher$fetchNetwork$1.invokeSuspend(CalendarFetcher.kt:0)
	at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:33)
	at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:106)
	at kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely(CoroutineScheduler.kt:570)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask(CoroutineScheduler.kt:750)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker(CoroutineScheduler.kt:677)
	at kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run(CoroutineScheduler.kt:664)
Caused by: net.fortuna.ical4j.data.ParserException: Error at line 107:Expected [61], read [10]
	at net.fortuna.ical4j.data.CalendarParserImpl.assertToken(CalendarParserImpl.java:486)
	at net.fortuna.ical4j.data.CalendarParserImpl.access$700(CalendarParserImpl.java:56)
	at net.fortuna.ical4j.data.CalendarParserImpl$ParameterParser.parse(CalendarParserImpl.java:357)
	at net.fortuna.ical4j.data.CalendarParserImpl$ParameterParser.access$2000(CalendarParserImpl.java:335)
	at net.fortuna.ical4j.data.CalendarParserImpl$ParameterListParser.parse(CalendarParserImpl.java:330)
	at net.fortuna.ical4j.data.CalendarParserImpl$PropertyParser.parse(CalendarParserImpl.java:266)
	at net.fortuna.ical4j.data.CalendarParserImpl$PropertyParser.access$1100(CalendarParserImpl.java:241)
	at net.fortuna.ical4j.data.CalendarParserImpl$PropertyListParser.parse(CalendarParserImpl.java:226)
	at net.fortuna.ical4j.data.CalendarParserImpl$ComponentParser.parse(CalendarParserImpl.java:446)
	at net.fortuna.ical4j.data.CalendarParserImpl$ComponentParser.access$900(CalendarParserImpl.java:422)
	at net.fortuna.ical4j.data.CalendarParserImpl$PropertyListParser.parse(CalendarParserImpl.java:224)
	at net.fortuna.ical4j.data.CalendarParserImpl.parseCalendar(CalendarParserImpl.java:128)
	at net.fortuna.ical4j.data.CalendarParserImpl.parseCalendarList(CalendarParserImpl.java:194)
	at net.fortuna.ical4j.data.CalendarParserImpl.parse(CalendarParserImpl.java:163)
	at net.fortuna.ical4j.data.CalendarBuilder.build(CalendarBuilder.java:197)
	at net.fortuna.ical4j.data.CalendarBuilder.build(CalendarBuilder.java:185)
	at at.bitfire.ical4android.ICalendar$Companion.fromReader(ICalendar.kt:89)
	... 11 more

[ArnyminerZ]

I'd say that the DESCRIPTION field is missing two spaces at the beginning of the new lines, so instead of being

DESCRIPTION:Test
<br>Test-Test\;

It would be:

DESCRIPTION:Test
  <br>Test-Test\;

See the examples provided by icalendar.org.

It's that way because otherwise it would be hard to know if the line below is a new property or the continuation of the previous one, in this case the DESCRIPTION.

[graue70]

Thanks for the hint @ArnyminerZ.

Are you saying that the standard requires those two spaces? Or are you saying that icsx5 requires the two spaces even though the standard does not?

(Like I mentioned: The validator says the file is fine. Also, Thunderbird Lightning has no problem with the file.)

[ArnyminerZ]

See the explanation here.

Lines of text SHOULD NOT be longer than 75 octets, excluding the line break. Long content lines SHOULD be split into a multiple line representations using a line "folding" technique. That is, a long line can be split between any two characters by inserting a CRLF immediately followed by a single linear white-space character (i.e., SPACE or HTAB). Any sequence of CRLF followed immediately by a single linear white-space character is ignored (i.e., removed) when processing the content type.

It's required by the standard. I don't know how Thunderbird handles it, are you sure that the whole description is being loaded and not just the first line?

Respecting the validator... Maybe there's a bug, I'm not sure

[graue70]

You were right. Now the validator gives an error when validating the example above. Thunderbird must have applied some magic to make it work.