- You cannot sign in Microsoft Lync Online server.
- Sometimes, you cannot search contacts in Microsoft Lync 2013 (Microsoft Skype for Business).
- Install the December 8, 2015 security update (KB3114351) for Lync 2013 (Skype for Business).
- Set the value of the HttpProxyControlFlags GPO to 3.
Note The new HttpProxyControlFlags GPO are located in the following registry subkeys:
The default value of the new HttpProxyControlFlags GPO is 0. This instructs the Lync 2013 (Skype for Business) client to set proxy settings for the Microsoft Online Services Sign-In Assistant (MOS SIA) component.
A value of 3 indicates that the MOS SIA component controls the proxy settings by itself.