Calendar import problem from Horde exporter

Symptoms

Calendar events fail to load in Roundcube. The error log returns the following message.

[21-Jul-2024 00:54:20 UTC] PHP Fatal error: Uncaught Sabre\VObject\InvalidDataException: 
Unknown value for FREQ=YEARLY\ in /usr/local/cpanel/base/3rdparty/roundcube/plugins/carddav/vendor/sabre/vobject/lib/Recur/RRuleIterator.php:736

Description

When Horde was removed, events in the SQLite database were exported to be imported automatically into Roundcube. We learned recently that some exported events failed to import due to a formatting issue in the event frequency value in version 120, which also removed CCS.

We've opened an internal case for our development team to investigate this further. For reference, the case number is HB-7790. Follow this article to receive an email notification when a solution is published in the product. 

Workaround

Remove the ICS files from the user's calendar folders that contain invalid syntax. You can identify offending files with the following search in the terminal/SSH.

grep -Rl 'FREQ=YEARLY\\' /home/*/.caldav/*/calendar/
grep -Rl 'FREQ=MONTHLY\\' /home/*/.caldav/*/calendar/
grep -Rl 'FREQ=WEEKLY\\' /home/*/.caldav/*/calendar/
grep -Rl 'FREQ=DAILY\\' /home/*/.caldav/*/calendar/

Related entries will contain the following syntax:

RRULE:FREQ=YEARLY\;INTERVAL=1\;UNTIL=9999-12-31 23:59:59\;

You can also repair an entry by modifying the rule to the following syntax:

RRULE:FREQ=YEARLY;INTERVAL=1;UNTIL=9999-12-31 23:59:59;