Error: content provider returned null on insert

[rutgerhendriks]

Problem scope

• I'm sure that this is a DAVx⁵ problem.

App version

• I'm using the latest available DAVx⁵ version.

Android version and device/firmware type

Android 14 and 16

Steps to reproduce

I exported a calendar event from my old phone and imported it into an agenda in Nextcloud.
In DAVx5 I enabled syncing for the agenda.
Now DAVx gives an error 'content provider returned null on insert' every time it syncs.
Without this calendar event, the error does not show.
Is it DAVx that generates the error? Or Android? Is it because of the DTEND that is set to 1970? Is there anything DAVx can do to prevent the error and thus not show the notification all the time?

BEGIN:VCALENDAR
CALSCALE:GREGORIAN
VERSION:2.0
PRODID:-//KF Software House//New Calendar//EN
BEGIN:VEVENT
DTSTAMP:20251126T113643Z
DTSTART:20251229T073000
DTEND:19700101T010000
SUMMARY:ExampleFailure
TZID:Europe/Amsterdam
UID:d9219865-8cfd-47ba-841a-58d86645f821
STATUS:TENTATIVE
TRANSP:OPAQUE
RRULE:FREQ=WEEKLY;BYDAY=MO,TU,TH,FR
ORGANIZER:mailto:email@example.com
END:VEVENT
END:VCALENDAR

Actual result

No response

Expected result

No response

Further info

No response

[ArnyminerZ]

Hi, have you got control over the ICS? RFC5545 clearly specifies that DTEND must be after DTSTART:

The value type of this property MUST be the same as the "DTSTART" property, and its value MUST be later in time than the value of the "DTSTART" property.

So this is out of spec, and it's behavior is uncontrolled.

[rfc2822]

Similar to #1850 (comment)

Please follow up in bitfireAT/synctools#147

[rutgerhendriks]

The ics is exported from my phone using the Calendar Backup app from KF Software House as found on the Play store and then imported in Nextcloud.
One of those probably mangled the ics then. The result though is that DAVx got an error when syncing it, so anything you can do to handle these faulty ics's is much appreciated and anyway smart to prevent garbage in when reading an ics from somewhere else.

[rfc2822]

Will be included in 4.5.7