The mute and unmute hotkey triggers an unread conversation in Skype for Business 2016 like there's a missed call

Symptoms

When you open a conversation that doesn't have audio in Microsoft Skype for Business 2016. The Hotkey process doesn't check if the audio is connected before you try to mute or unmute. As a result, the conversation shows an error alert and flashes the frame.

Resolution

To fix this issue, install the December 6, 2016, update (KB3127980) for Skype for Business 2016.