Cannot Synchronize Address Book: Resolved

Like most of the users I too used to get “Cannot Synchronize Address Book” notification whenever i used to login in my OCS Communicator client. This happened when we do custom installation of any application, do not configure optional features etc.

I used to ignore that notification most of the time except today. I got irritated by yellow exclamation mark comnot on Communicator Icon in system tray and I decided to hunt down the problem.
I didnt do much on my own except following paths shown by Google. I searched for a while, went through some forums and fixed the problem(s).

This post is to summarize the working steps gathered from different forums. Following are the steps that i followed in the process.

  • Open the Office Communications Server 2007 management console and Expand server running with web components service.


  • From the Available Task in right pane, Expand Validation and Select and complete the Web Components Server Validation wizard.
    • If wizard failes with Connectivity error “Failure [0xC3FC200D] One or more errors were detected.” then problem is Default website on Web Component Server is not assigned with valid/no  certificate. Refer here to fix this.
    • If the Validation Wizard fails with GroupExpansion and AddressBookServer Configuration then the problem is because Windows Server 2003 SP1 includes a new security feature named loopback check functionality. Validation wizard tries to visit following URL’s but fails  due to authentication failure. However, if you visit the same URL’s from system; other than Web Component Server, it works perfectly.
    • Microsoft has already documented workarounds for these error. Follow the references and you are through.
  • Once the problem is resolved you can search needed users contact details as shown in following screen shots.      I am now happy to see my communicator free from Yellow Exclamation mark 🙂



  1. Assign Certificate to Default Web Site
  2. Workaround for Loopback Check

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