/tmp/horde.log contains
Apr 23 22:14:03 HORDE [error] [kronolith] Support for Date_Holidays has been enabled but the package seems to be missing. [pid 12352 on line 488 of "/var/www/kolab/htdocs/horde/kronolith/lib/Kronolith.php"]
Kronolith is looking for Date/Holidays.php on line 472
http://projects.pardus.de/kolab/browser/horde-cvs/kronolith/lib/Kronolith.php?rev=2110There is no such file, there is a file called holidays.php in horde/kronolith/lib/drivers however changing the location to that breaks Kronolith.