Event ID 27: Calendar property is missing or empty

After applying Office 2010 Service Pack 2 or one of the last updates that were released for Service Pack 1 (KB2817371 or later), you may see the following warning popping up multiple times in the Application Log of the Event Viewer:

Source: Outlook
EventID: 27
Description: Calendar Folder Property is missing

Office 2010 Service Pack 2 is safe to use

While it might seem scary to suddenly have that many warning events, investigation by the Outlook Team shows that there is no actual harm done to the system and the issue is basically “purely cosmetic”.

This means that there isn’t any direct need to uninstall SP2 and proceeding deployment of SP2 is fully supported.

A fix for this issue will be part of the December 2013 update for Outlook 2010 (released on December 10 to be precise).

The KB article for this issue is: KB2883156: Event ID 27, “Calendar Folder property is missing,” after you apply Office 2010 SP2.

There is also a quite vocal thread with additional information about this issue in the Outlook IT Pro TechNet forum.

Solutions and alternatives

A warning event is logged upon starting Outlook for each Calendar that you have when you have a pst-file attached to your mail profile.

Currently, the proposed solution in the KB article is to remove any pst-files from your mail profile.

While this may be a viable solution when you only have an Exchange account or Outlook Hotmail Connector account configured in your mail profile, it certainly isn’t possible to do this when you have a POP3 or IMAP account configured in Outlook or are also connected to a SharePoint Server or Web Calendars.

As mentioned previously, the warnings can be safely ignored. However, if you want them out of your Event Viewer, you can hide them by applying a filter.

  1. Use the “Filter Current Log…” link in the Actions pane of the Event Viewer or from the right click menu on “Application” under Windows Logs.
  2. Specify the following:
    • Event level: Warning
    • Event sources: Outlook
    • Includes/Excludes Event IDs: -27

To set the exclude filter, don’t forget the minus ( – ) in front of 27. (Click on image to enlarge)
To set the exclude filter, don’t forget the minus ( – ) in front of 27.
(Click on image to enlarge)

Don’t worry about your Event Log or hard disk filling up: By default, the Application log will only grow up to 20MB and will automatically purge older items when this size has been reached.

In praxis this means that it can keep over 25.000 events which, for the average system, is almost a year back. The amount of items logged by this Outlook bug is hardly affecting that.