XADM: Outlook Client May Error When Updating Free and Busy

The Outlook client may fail to update its Free and Busy information and a pop-up error message displays the following: Also, users may not be able to view other users' Free and Busy times when planning meetings and inviting others.

There can be a variety of reasons for this error. Most typically, network problems are preventing the client's connection to the Site-Folder-Server. This article documents the specifics of a rare case.

The Exchange Server information store is comparing the local site name passed in by the client with the list of Site-Folders within the organization. The local site name is determined to be lacking from among those in the list, even though the System Folders hierarchy in the Exchange Server Administrator program displays a Free and Busy folder for the site. For details, see the MORE INFORMATION section below.

To resolve this problem, obtain the latest service pack for Exchange Server version 5.5. For additional information, click the following article number to view the article in the Microsoft Knowledge Base: The English version of this fix should have the following file attributes or later: If you are applying the post-SP2 hotfix, please apply both the information store and directory hotfix.

This FTP site contains both the information store and directory hotfix build 5.5.2600 and later:

Microsoft has confirmed that this is a problem in Microsoft Exchange Serverversion 5.5. This problem was first corrected in Exchange Server 5.5 Service Pack 3.

An incorrect assumption was being made regarding the sort order of the list that the passed in site name would be checked against.

This problem could only occur with similarly named site names if:

• A differing "symbol" character exists in the same position of the names.
• The passed in value's symbol character had an ASCII value less than some element location in the list that precedes the passed in site name's element position.

For example:

If the following site name: was compared against a list sorted in the following order: The string, EXCH-0B, is compared character by character with each entry in the list beginning with the first entry, EXCH_0A. The ASCII hex value for a dash is 2D, and for an underscore it is 5F. Because 2D is less than 5F, and the assumption was made that the list is sorted in ASCII sort order (including symbol characters), it can be concluded that EXCH-0B is not in the list.

The fix was to anticipate the proper sort order when passing in the site name for comparison.