[Synology] Unsupported operand types: string + string in RRule.php

[devvv4ever]

There seem to be certain recurring events (RRULEs) where Synology Calendar v2.5 is crashing when it wants to process it.

The error occurs on a REPORT on a resource like http://192.168.10.42:5000/caldav.php/username/home/ and throws an exception.

HTTP REQUEST
Request{method=REPORT, url=http://192.168.10.42:5000/caldav.php/username/home/, headers=[Depth:1, User-Agent:DAVx5/4.4.1.1-gplay (2024/07/12; dav4jvm; okhttp/4.12.0) Android/14, Accept-Language:de-DE, de;q=0.7, *;q=0.5]}
<?xml version='1.0' encoding='UTF-8' ?><CAL:calendar-query xmlns="DAV:" xmlns:CAL="urn:ietf:params:xml:ns:caldav"><prop><getetag /></prop><CAL:filter><CAL:comp-filter name="VCALENDAR"><CAL:comp-filter name="VEVENT"><CAL:time-range start="20240415T071927Z" /></CAL:comp-filter></CAL:comp-filter></CAL:filter></CAL:calendar-query>

HTTP RESPONSE
Response{protocol=http/1.1, code=500, message=Internal Server Error, url=http://192.168.10.42:5000/caldav.php/username/home/}
Exception [0] Unsupported operand types: string + string
At line 138 of /volume1/@appstore/Calendar/davical/inc/RRule.php
================= Stack Trace ===================
/volume1/@appstore/Calendar/davical/htdocs/caldav.php[109] include_once()
/volume1/@appstore/Calendar/davical/inc/caldav-REPORT.php[251] include()
/volume1/@appstore/Calendar/davical/inc/caldav-REPORT-calquery.php[467] expand_event_instances()
/volume1/@appstore/Calendar/davical/inc/RRule.php[1490] Rfc5545Duration->equals()
/volume1/@appstore/Calendar/davical/inc/RRule.php[109] Rfc5545Duration->asSeconds()

This needs to be reported to Synology directly. It should be fixed in the davical/inc/RRule.php around line 138.

[rfc2822]

Has this already been reported to Synology?

[devvv4ever]

Has this already been reported to Synology?

not yet... do you think this is enough information for Synology so that they can find/fix this?

[rfc2822]

Yes, it's a specific PHP line so that should be enough to at least have an idea what this is about.

[devvv4ever]

I've reported it now: It is tracked in Synology ticket #3634897 Let's leave it open until we get a response/confirmation by them.

[rfc2822]

Their response:

For further handling on the issue, our developers would require the following items and confirmation:

• A debug.dat file with the Calendar package and a remote session to the device?

• Additionally, can the issue be consistently reproduced on every NAS and DAVx5 for Android device?

• To better understand the error, could you confirm if it occurs automatically when modifying the RRULE event on the mobile phone? A screen recording would be very helpful.

• Also, ensure that the NAS has been updated to DSM version 7.2.1-69057 Update 5 and Calendar to version 2.5.1-21153.

Do not hesitate to contact me, if you have any further questions.

[Rudi4000]

I had this problem, too, and will provide the requested info later today. I synchronised Outlook 2013 calendar with Synology Calendar via CalDavSynchronizer on Windows 10 and Samsung Galaxy A53 and Tab S9FE via DAVx5. The failure was always the same, but the interesting thing was that it happened after the update from Synology Calendar v2.4 to v2.5. After a new set up of the calendar without recurring events the problem was solved, but I couldn't find out with recurring event it caused.

[Rudi4000]

I am using Synology Calendar v2.5.1-21153 and Synology DSM 7.2.1-69057 Update 5. "To better understand the error, could you confirm if it occurs automatically when modifying the RRULE event on the mobile phone? A screen recording would be very helpful." => The error occurred whenever I synchronised. Since I couldn't find out which reuccing event caused the error, I couldn't change the event. However, I first deleted all recurring birthday events and the error was still there. Second I deleted all recurring events in Outlook and synchronised and the error was still there.

[rfc2822]

Has this been a problem recently? Can we close the issue? At least it seems so according to Synology Calendar change logs:

[devvv4ever]

Nothing changed... The issue was auto-closed on Synology ticket system meanwhile since they did not seem to continue to investigate. The "Fixed Issue" is the changelogs is most likely something else.

[rfc2822]

Well it's not our bug so is there any use in keeping it open here?

[devvv4ever]

The user reported that it was fixed by reinstalling the Calendar package while also exporting and importing the ical data back again.