This problem was solved when we went up the version of PHP. From 4.3.9 
to 5.1.6

Please create a new ticket of this. This might be a completely 
different issue.

Sorry, forgot to mention these lines are found in the apache errorlog.

Hi, maybe I can be of some assistance. I run , Horde Groupware Webmail 
Edition 1.2.7 on my own server (thus having administrator access). 
Simple installation, no tweaks! I use "Funambol Outlook Sync Client 
8.7.2" to connect my Outlook client to horde.

When I add a birthday in Outlook (which is a yearly recurrent event) 
and I synch this trough "rpc.php", then it appears in de calendar of 
Horde. Now when I synch on another PC (with an 'empty' Outlook). the 
birthday isn't synched back! No problems with daily, weekly and 
monthly recurrent events.

PHP Warning:  date() expects parameter 2 to be long, array given in 
/var/www/html/horde/lib/SyncML/Device/Sync4j.php on line 1028
PHP Warning:  date() expects parameter 2 to be long, array given in 
/var/www/html/horde/lib/SyncML/Device/Sync4j.php on line 1030

I checked the code and found:

line 1028 => $hash['DayOfMonth'] = date('j', $start);
line 1030 => $hash['MonthOfYear'] = date('n', $start);

I have debugged the value of '$start' while syncing again with the 
other PC. It appears that '$start' is an array like the one below:

array('mday' => '21', 'year' => '1976', 'month' => '05')

The date function doesn't accept this as value, thereforce synching 
recurrent yearly events fails...

If you need more info, please mail me.

We can't you help debugging the problem if you don't have access to 
the Horde system. Please talk to your administrator.

I Can't  follow the suggested steps because I am only an user without 
access to the Horde server.

I'm going to be more explicit:

First Test: Step to step

1.- I have an empty Calendar in Horde (Horde Groupware Webmail Edition 
1.25 with Kronolith 2.3.3).
2.- I have  no SyncML information: No entries in Options-->Global 
Options-->SyncML
3.- I introduce an Recurrent "All day" event at 27th of February. It 
occurs every 1 year on the same date.  The event is attached at 
Only-One-Event.ics file.
4.- I have un Outlook 2007 with Funambol 8.0.5
5.- In Outlook the calendar is empty.
6.- I sync Calendar : two way. Horde<-->Funambol
7.- The sync process finish OK.
8.- Calendar in Outlook is empty. That means "Nothing occurs".
9.- In the file  Funambol-sync-log.txt is the debug provided for Funambol.

------------------------------------------

Second Test: Step to step

1.- I have the calendar of the previous test in Horde.
2.- I Clean SyncML information in Options-->Global Options-->SyncML.
3.- In Outlook there is no events in Calendar
4.- With Funambol I do a recover "Replace all of the Outlook data with 
data from the server" for Calendar.
5.- During the process it inform that 1/1 is recover. In the file 
Funambol-recover-log is the log of the operation.
6.- But in Outlook, in 27-02-2010 there is not any event.
7.- I realize that the event is in 01-02-2011. In File 
Outlook-Event.ics is the event.
------------------------------------------

Third Test: Step to step

1.- I have the calendar of the previous test  in Horde.
2.- I Clean SyncML information in Horde.
3.- I have a Telephone HTC with Windows Mobile 6.1 and  Funambol 8.0.4
4.- In the phone from Funambol I do a "cleanup" of the calendar to 
ensure that the calendar is empty.
5.- In the phone I sync (two-way).
6.- After finishing the sync process successfully the Calendar is 
empty in the phone.
----------
Thank you for your patience

What do you mean with "nothing occurs"? Is the event not being added 
to the event table?
Also please read http://wiki.horde.org/SyncMLProblemReport and follow 
the steps to generate complete SyncML debugging information.

Initial situation:

        Horde Groupware Webmail Edition 1.2.5
        Kronolith 2.3.3

A new user with no events  in his calendar and without SyncML information.

He introduces an "All day"  recurrent event as Yearly: Recurs every 1 
years on the same date.

After that:
        In Outlook 2007 with Funambol 8.0.5.
                Doing a sync   -->nothing occurs
                Doing a recover: Replace all of the Outlook Data with data from de 
Server --> nothing occurs.

        In a phone with Windows Mobile 6.1 and Funambol 8.0.4.
                Do a sync  --> Nothing occurs.