Knowledgebase: Exchange
Recurring events show wrong time when crossing Daylight Saving Time
Posted by Matt Kuebler on 06 November 2009 11:47 AM


This issue involves recurring series events, created on the device, which cross over the Daylight Saving Time (DST) range. 
 - Those created outside DST (Nov-March):  Occurrences which then fall during DST (March-Nov) synchronize to the server 1 hour late. 
         (EX)      Series:  Occurs the 20th of each month, beginning in December, for 6 months.
                     Result:  Mar.20, Apr. 20, May 20 occurrences appear 1 hour late on the server.

- Those created during DST (March-Nov):  Occurrences which then fall outside DST (Nov-March) synchronize to the server 1 hour early.
         (EX)      Series:  Occurs the 15th of each month, beginning in September, for 6 months.
                     Result:  Nov. 15, Dec. 15, Jan. 15, Feb. 15 occurrences appear 1 hour early on the server.

A related issue involves daily recurring all-day events and single all-day events created, on the device, during DST (March-Nov).  The events start/occur one day late when synchronized to the server.


Fixes:  At present, one of following manual fixes is necessary.

  • If there are no legitimate exceptions to the series, edit the series on the server side.  All occurrences will be updated correctly on the server and will synchronize to the device. 
  • If there are legitimate exceptions that you wish to preserve, edit each of the incorrect occurrences individually on the server side.

Prevention:  To prevent this issue from occurring, create recurring series (those that will cross over the DST range) on the server and do not make changes to the full series from the device.  Changes to individual instances from the device will synchronize properly.