Microsoft Skype for Business client may crash when you do one of the following in Microsoft Outlook:
You open a Skype meeting that contains an external contact.
You select an email that has an external contact in the To line.
This issue may occur in Skype for Business 2016 and Skype for Business 2015 (Lync 2013).
To fix this issue, install one of the following updates:
For Skype for Business 2016, install the February 6, 2018, update (KB4011662).
For Skype for Business 2015 (Lync 2013), install the February 6, 2018, update (KB4011678).
Note Lync 2013 was upgraded to Skype for Business in April 2015.