Event ID 27 and Calendar Folder property is missing error occurs after you apply Office 2010 SP2

Original KB number:   2883156


After you apply Microsoft Office 2010 Service Pack 2 (SP2) or hotfixes released after SP2, users may see many Event ID 27 warnings from Outlook in the Application log. This issue occurs for users who have a PST attached to their profile. This includes PSTs that were created by connecting to a Microsoft SharePoint site.

The following is an example event in the Application log:

Log Name: Application
Source: Outlook
Date: DateTime
EventID: 27
Task Category: None
Level: Warning
Keywords: Classic
User: N/A
Computer: ComputerName
Calendar Folder Property is missing


To work around this problem, PSTs can be removed from the profile. To remove PSTs from your Outlook profile, follow these steps:

  1. Open Microsoft Outlook 2010.
  2. Select File, and then select Account Settings.
  3. Select the Data Files tab.
  4. Select the data file that you want to remove, and then select Remove.

Removing PSTs from your profile will not remove the PSTs from your system. Removing some PSTs may result in loss of functionality in Outlook. For example, removing the SharePoint Lists PST will remove connections to SharePoint sites.