I think this was fixed in 2.1 already by bug #3243.  Can you try this patch?



http://cvs.horde.org/diff.php/kronolith/lib/Driver.php?r1=1.116.2.33&r2=1.116.2.34&ty=u



Or upgrade to a 2.1 snapshot.

Sun's Calendar Express exports calendars in iCalendar format, and some 
repeating events appear to only have a DTSTART tag, no DTEND tag.   
When this happens, the DTSTART tag always has the parameter 
VALUE=DATE.  I've attached a sample event from a real calendar that 
shows this. When trying to import a calendar with such an event, 
Kronolith errors out.



The iCalendar standard isn't crystal clear on whether or not this is 
okay, but the RFC does contain an example where it apperas that there 
is no DTEND tag, which suggests that Sun's Calendar does the right 
thing and Horde does not.  The example from RFC 2445:



  Example: The following is an example of the "VJOURNAL" calendar

    component:



      BEGIN:VJOURNAL

      UID:19970901T130000Z-123405@host.com

      DTSTAMP:19970901T1300Z

      DTSTART;VALUE=DATE:19970317

      SUMMARY:Staff meeting minutes

      DESCRIPTION:1. Staff meeting: Participants include Joe\, Lisa

        and Bob. Aurora project plans were reviewed. There is currently

        no budget reserves for this project. Lisa will escalate to

        management. Next meeting on Tuesday.\n

        2. Telephone Conference: ABC Corp. sales representative called

        to discuss new printer. Promised to get us a demo by Friday.\n

        3. Henry Miller (Handsoff Insurance): Car was totaled by tree.

        Is looking into a loaner car. 654-2323 (tel).

      END:VJOURNAL



(From page 56.)



Using the SQL driver, the error happens on line 784:



783>       // Event end.

784>        $this->_properties['event_end'] = date('Y-m-d H:i:s', 
$this->end->timestamp());



The call to a method $this->end errors out because there is no end 
explicitly specified.