OCS 2007 R2: Cannot synchronize with the corporate address book


  • Hello everyone

    We have an error synchronizing the address book from Office Communicator R2 clients connected through Internet. For internal users, the address book is right download.

    In our environment, we have an Edge Server and a Reverse Proxy (TMG 2010). The rule in TMG is rightly configured.

    The error in OC client is: "Cannot synchronize with the corporate address book. This may be because the proxy server setting in your web browser does not allow access to the address book. If the problem persists, contact your system administrator"

    However, we’ve tried accessing external URL from Internet without problems (certificate is OK).

    Office Communicator Configuration Information shows the correct information.

    Testing these URLs from IE, the credentials are prompted and the webpages and files are correctly downloaded:


    The file is correctly downloaded.


    Additionally, we have the following error in TMG logs when OC client try to download the files:


    However, I try downloading the files from IE, and it works!

    Any ideas?

    Thanks in advance

    Javier Mariani

    Thursday, August 30, 2012 7:35 PM


  • Hi,

    Please refer this solution of the following article about this issue:

    Please remember to click “Mark as Answer” on the post that helps you, and to click “Unmark as Answer” if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.

    Friday, August 31, 2012 7:39 AM
  • Hi

    Thanks for all replies

    We found the problem: The CA root certificate had a bad CRL. So, the client  was unable to validate the certificate and the address book could not be downloaded.

    The Fiddler2 tool helped us for troubleshooting.

    Thanks again


    Javier Mariani

    Thursday, September 6, 2012 6:50 PM

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