The Lync 2010 client or the Office Communicator client does not download the corporate address book and displays a notification: "Cannot Synchronize Address Book"

Consider the following scenarios:

• You use the Microsoft Lync 2010 client to log on to the Microsoft Lync Server 2010.
• You use the Microsoft Office Communicator client to log on to the Communications server.

In these scenarios, the corporate address book does not download, and no results are displayed when you search contacts by name.

Also, you receive the following notification in the Lync 2010 client or in the Communicator client:



When you click the notification to display the details, you receive the following error message:

Communicator 2007



Lync 2010 or Communicator 2007 R2



If you run the Validation Wizard on the Communications Server 2007 R2 or Communications Server 2007 front-end server, you receive the following error message in the log:



In the Validation Wizard log, expand Diagnose WebComponents, expand Check Connectivity, and then expand Checking Address Book Serverconfiguration. The URL of the location to download the address book is displayed in the Check Http URL field together with the following error message:



Note: Lync Server 2010 does not have a validation wizard.

This issue occurs if the website that hosts the address book does not have a valid Secure Sockets Layer (SSL) certificate installed.

To resolve this issue on a computer that is running Windows Server 2003, make sure that the website that is hosting the address book has a valid SSL certificate installed. To do this, follow these steps:

1. On the computer that is running Internet Information Services (IIS), click Start, click Run, type inetmgr.msc, and then click OK.
2. Expand ComputerName (local computer), expand Web Sites, right-click the website that hosts the address book, and then click Properties.
3. Click the Directory Security tab.
4. In the Secure communications section, determine whether View Certificate is enabled.
   
   Note If View Certificate is enabled, click View Certificate. Then, you can determine whether the certificate is valid.
   • If the certificate is invalid, follow these steps:
     1. Click Server Certificate in the WebSiteName Properties dialog box.
     2. Click Next, and then click Renew the current certificate. Or, click Replace the current certificate.
     3. Follow the steps to finish the IIS Certificate Wizard.
        
        Note The IIS Certificate Wizard will help you renew your certificate or replace your certificate with a valid certificate.
        
        For more information about how to request a certificate and install the certificate in IIS, click the following article number to view the article in the Microsoft Knowledge Base:
        299875  (http://support.microsoft.com/kb/299875/ ) How to implement SSL in IIS
   • If View Certificate is disabled, no certificate is installed on this computer. You have to install a certificate to this website. To do this, follow these steps:
     1. Click Server Certificate in the WebSiteName Properties dialog box.
     2. Click Next, and then click Create a new certificate.
     3. Follow the steps to finish the IIS Certificate Wizard.
        
        Note The IIS Certificate Wizard will help you install a certificate to this website.
        
        For more information about how to request a certificate and to install the certificate in IIS, click the following article number to view the article in the Microsoft Knowledge Base:
        299875  (http://support.microsoft.com/kb/299875/ ) How to implement SSL in IIS

To resolve this issue on a computer that is running Windows Server 2008, make sure that the website that is hosting the address book has a valid SSL certificate installed. To do this, follow these steps:

1. 1. On the computer that is running Internet Information Services (IIS 7.0), click Start, click Run, type inetmgr.msc, and then click OK.
2. Expand ComputerName (local computer), expand Web Sites, click the website that hosts the address book, and then click Bindings in the Actions pane.
3. Select the HTTPS site binding that includes the port that the Address book Service is listening on, and then click Edit.
4. Click View to open the certificate dialog box, and then view the expiration date of the certificate on the General tab.
   
   Note The IIS Server Certificate feature helps you renew your certificate or replace your certificate with a valid certificate.
   • If the certificate is invalid, follow these steps:
     1. In the Connections pane, select the name of the IIS 7.0 server that hosts the Address Book service, select the Features view, and then click Server Certificates.
     2. In the Actions pane, select Open Feature.
     3. In the Features view, select the certificate that you viewed in step 4, and then use the Actions pane to renew the certificate.
   • If the needed certificate is not installed on this computer, use the certificate wizards in the Actions pane to do one of the following: Import, Create a Certificate Request, Complete a Certificate Request, or Create a Domain Certificate.
   • For more information about how to renew, create, and complete certificate requests on IIS 7.0, visit the following Microsoft website: http://technet.microsoft.com/en-us/library/cc732230(WS.10).aspx (http://technet.microsoft.com/en-us/library/cc732230(WS.10).aspx)