Lync 2010 – Error “Cannot synchronize address book”

Whilst signed into Microsoft Lync, you may notice an error at the bottom of the client “Cannot synchronize address book”. You are also unable to find new Lync users. To resolve this issue, you can force address book updates on the client:

  • Sign out of the Lync client and close the application from the system tray
  • Browse to %USERPROFILE%AppDataLocalMicrosoftCommunicatorsip_username@sipdomain (Windows Vista/7) or %userprofile%Local SettingsApplication DataMicrosoftCommunicatorsip_ (Windows XP)
  • Delete files named GalContacts.db and GalContacts.db.idx (you may notice the date stamp on these to be out of date)
  • Add the following entry to the clients registry:

32bit Clients:

Windows Registry Editor Version 5.00

64bit Clients:

Windows Registry Editor Version 5.00


  • Sign back into Lync (it may take a few moments to recreate the GALContacts files again)
  • The address book error should now be cleared and new Lync users will appear in the search

UPDATE 05/09/2012

I came across this error again today, but this time every user was experiencing the “Cannot synchronize address book” error in their Lync client.  I tried to force my client to update the address book using the fix above but this did not work.

I checked the event logs on all Lync servers but was unable to find an error relating to the address book service.  I could see that the address book was being updated within the file store.  I then tested the Address Book web service using the following PowerShell commands:

$credentials = get-credential

Test-CsAddressBookService –TargetFqdn -UserCredential $credentials -UserSipAddress “sip:[email protected]


This returned an error:

Result     : Failure
Latency    : 00:00:00
Error      : ERROR – No response received for Web-Ticket service

After trawling through various posts online which suggested re-submitting the Lync Topology, checking the File Store permissions, none of which worked.  In the end a simple reboot of my Lync Front End server resolved the problem.

4 Replies to “Lync 2010 – Error “Cannot synchronize address book””

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