After you install the December 2015 update for Microsoft Lync 2013 (Skype for Business), you receive the following error message when you try to start Lync 2013:
Lync is becoming Skype for Business. To run this app, you need to install additional updates for Skype for Business. See KB3115883 for details or contact your administrator.
This problem occurs because security update MS15-044 is not installed on your device. MS15-044 is a prerequisite for the June 2015 Lync (Skype for Business) update and later versions of the update.
Article ID: 3115883 - Last Review: Jan 5, 2016 - Revision: 1
Microsoft Lync 2013, Microsoft Lync Basic 2013