When you try to search the address book Microsoft Lync, you receive one of the following error messages:
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.
The address book is preparing to synchronize. Search results might not be current.
In Skype for Business Online, address book and GAL lookups are performed through web requests only. The Lync client doesn't download and save a local copy of the address book any longer. This reduces the load on the servers, and it provides the most up-to-date information possible when you perform a contact search.
Try to verify that connectivity to the Address Book Web service is available. To do this, follow these steps: