Summary
Assume that you aren't signed in to Microsoft Skype for Business 2016, and you try to join a meeting by clicking a meeting join link. When the sign-in process takes too long (for example, more than 10 seconds), Lync Web App will start.
How to get this update
To get this update, install the April 4, 2017, update (KB3178717) for Skype for Business 2016.
