Appointments do not show in the app but are created in the synchronized calendar

[MichaelMeierOneFive]

Checklist

• I can reproduce the bug with the latest version given here.
• I made sure that there are no existing issues - open or closed - to which I could contribute my information.
• I made sure that there are no existing discussions - open or closed - to which I could contribute my information.
• I have read the FAQs inside the app (Menu -> About -> FAQs) and my problem isn't listed.
• I have taken the time to fill in all the required details. I understand that the bug report will be dismissed otherwise.
• This issue contains only one bug.
• I have read and understood the contribution guidelines.

Affected app version

1.8.1

Affected Android/Custom ROM version

Orphene OS, release 2025112100

Affected device model

Pixel 7a

How did you install the app?

F-Droid / IzzyOnDroid

Which calendar service or provider do you use, if any?

Synology calendar (running on private Synology NAS)

Which sync adapter app do you use for calendar synchronization, if any?

DAVx5

Steps to reproduce the bug

1. Create a calendar for each of two users on a private NAS (Synology)
2. Add the two calendars to be synchronized through DAVx5
3. Activate the CalDAV sybchronization for both calendars
4. Select both calendar accounts
5. Create an appointment in each account

Expected behavior

If both calendars are connected and synchonized propperly, I expect to see the appointments of both calendars in the app and to be able to create, delete, and change them.

Actual behavior

Both calendars are connected and synchonized propperly, as DAVx5 connects without errors. Moreover, I can create appointments for both calendars in the app and they are thus synchonized accordingly. However, only the appointments of one calendar are visible, whereas those of the second calendar cannot be seen.

Screenshots/Screen recordings

The appointments of calendar1 are visible, whereas those of calendar2 cannot be seen.

App_calendarView.pdf

App_settings1.pdf

App_settings2.pdf

DAVx5_calendar1.pdf

DAVx5_calendar1_settings.pdf

DAVx5_calendar2.pdf

DAVx5_calendar2_settings.pdf

Thunderbird_calendarView.pdf

Additional information

No response

[naveensingh]

Are those events from the second calendar visible in other calendar apps (e.g., Etar) on the same device?

If you do not have any other calendar app, please install Etar to help identify the source of the problem.

[MichaelMeierOneFive]

I just installed Etar and yes, in Etar the events of both calendars are visible. I attached two print screens, the first from Etar and the second from Fossify.
Please note that I am happy to use Etar and thus this issue is not urgent for me. However, if you like to work on it, I am happy to assist as much as I can. Just let me know what I can do and what information I may provide you with.

Etar.pdf

Fossify.pdf

[naveensingh]

My guess is that there is at least one event (maybe added recently) in your second calendar that Fossify Calendar is silently failing to read from the Android calendar database, which in turn causes the remaining events to fail too. #268 is similar in this regard.

If possible, could you export and share that second calendar here or send it to hello@fossify.org (with personal information redacted)?

[MichaelMeierOneFive]

Sure. as I am unable to uplead the ICS file of my redacted calendar, I mailed it to you, putting the title of this issue in the subject.

[macpac59]

I experience similar problems with different calendars since a couple of weeks: Appointments are only synced after a couple of hours or even days. The sync between Synology based calendars and Fossify Calendar works faster than the sync between Nextcloud based calendars and Fossify Calendar. In Etar e.g. changes are shown immediately after a sync via DAVx⁵.

System specs:

• v1.9.0
• eOS 3.3 (Android 15)
• Fairphone 5

[macpac59]

A new update has been released but still no solution for this severe bug. 😕 Is there anything I can contribute for a solution?

[peckato1]

I have the same problem on my OnePlus 8T, fossify calendar and davx5 installed from fdroid.
This problem appears only on one calendar (my default one). I can still see old recurring events, but the new events are removed after they get created (and synced?). Etar sees the events. And i can see the events on my other devices.

Anything I can do to help?

[peckato1]

Ok so I learned how to debug my device and found the culprit. The problem at my end was that fossify calendar silently crashes on error while syncing events.

I have one event on the server which is (probably) massively broken. davx5 somehow processes it and then this lambda runs and throws an exception:

https://github.com/FossifyOrg/Calendar/blob/1.10.3/app/src/main/kotlin/org/fossify/calendar/helpers/CalDAVHelper.kt#L218

This is what i found in my log after wrapping the inner lambda inside a try-catch:

EXCEPTION processing event id=4311 title='Stěna' rrule='FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z
FREQ=WEEKLY;UNTIL=20260108T175959Z' dtstart=1741888800000 dtend=0 duration='PT3H' originalId=null originalInstanceTime=0
java.lang.IllegalArgumentException: Invalid format: "20260108175959
FREQ" is malformed at "175959
FREQ"
	at org.joda.time.format.DateTimeFormatter.parseDateTime(DateTimeFormatter.java:953)
	at org.fossify.calendar.helpers.Parser.parseDateTimeValue(Parser.kt:107)
	at org.fossify.calendar.helpers.Parser.parseDateTimeValue$default(Parser.kt:100)
	at org.fossify.calendar.helpers.Parser.parseRepeatInterval(Parser.kt:55)
	at org.fossify.calendar.helpers.CalDAVHelper.fetchCalDAVCalendarEvents(CalDAVHelper.kt:270)
	at org.fossify.calendar.helpers.CalDAVHelper.refreshCalendars(CalDAVHelper.kt:72)
	at org.fossify.calendar.activities.MainActivity.updateCalDAVEvents$lambda$26(MainActivity.kt:657)
	at org.fossify.calendar.activities.MainActivity$$ExternalSyntheticLambda5.invoke(D8$$SyntheticClass:0)
	at org.fossify.commons.helpers.ConstantsKt.ensureBackgroundThread$lambda$0(Constants.kt:529)
	at org.fossify.commons.helpers.ConstantsKt$$ExternalSyntheticLambda0.run(D8$$SyntheticClass:0)
	at java.lang.Thread.run(Thread.java:1564)

Unfortunately throwing here stops processing the synced events which means no further events are displayed in the calendar.

I am neither kotlin nor android developer so I am not rushing into fixing it, but catching the exception unbreaks my calendar.

The malformed VEVENT in case you want to simulate it yourself: event.txt

[ltguillaume]

So, in order to fix this:

1. Properly catch parsing errors
2. Instead of leaving the user in the dark, show an error message (notification) about which entry is corrupt, so the user can try to fix it.