ZCS 5.0.12_GA_2789.RHEL5_64
Outlook 2007 SP2, ZCO 5.0.2992.16
(also with Outlook 2007 SP1, Outlook 2003 and ZCO 5.0.12)

This issue is reported a few times a month in my environment: A calendar appointment will show in the web client, but it does not sync with Outlook.

The other day we noticed two recurring appointments in a resource calendar that do not sync to Outlook. Any users with whom this resource calendar has been shared do not see either of these two appointments in Outlook.

I even created an Outlook profile for the resource account and allowed it to completely sync. Neither of the two appointments appear in Outlook. One of the two appointments generates a "Local Failure Notice" email message.

These two appointments have been around for months and probably have been updated a few times. I can't say when they stopped syncing with Outlook.

The usual workaround is to delete and recreate the appointment. That's not ideal, of course, as it undermines user confidence in their calendar's accuracy.

I have ZCO logs for anyone willing to look at them. The appointment that generated the Local Failure Notice logs these entries (assuming I'm deciphering the logs correctly):

16-06-2009 12:35:16.503 [5104]: Zimbra::Mail::ZimbraApptToOOMAppt::MakeExceptionTo Recurrence. could not find occurrence for this date

16-06-2009 12:35:16.503 [5104]: Zimbra::Mail::ZimbraApptToOOMAppt:ealWithExceptions. MakeExceptionToRecurrence() failed on [1 of 1]

16-06-2009 12:35:16.503 [5104]: Zimbra::Mail::ZimbraApptToOOMAppt::Convert. ERROR - DealWithExceptions() failed.

16-06-2009 12:35:16.503 [5104]: Appointment conversion failed: could not find occurrence for this date(TZID=(GMT-08.00) Pacific Time (US & Canada):20090409T140000 Main appt time zone: Pacific Time (US & Canada))ERROR - Problem processing an exception. Inconsistencies may result

16-06-2009 12:35:16.503 [5104]: Zimbra::Mail::OOMHelper::Logoff.16-06-2009 12:35:16.768 [5104]: Zimbra::Sync::SaxHandlers::SyncSAXHandler::CreateA ppointment. done conversion

16-06-2009 12:35:16.768 [5104]: Zimbra::Sync::SaxHandlers::SyncSAXHandler::CreateA ppointment. ERROR - Appt or Task Conversion Failed.

16-06-2009 12:35:16.768 [5104]: Zimbra::Sync::SaxHandlers::SyncSAXHandler::CreateA ppointment. deleting message with mid [286], because calendar conversion failed.

My untrained eye has yet to spot any log entries related to the second appintment.

Any thoughts or suggestions are appreciated. Thanks.