Symptoms
This issue occurs in a Microsoft Lync Server 2013 environment when you try to share your desktop in an online meeting, and the meeting attendees include a group that has a large number of users (such as 50).
When this issue occurs, the desktop-sharing attempt fails. Additionally, the following diagnostic message is displayed in the Call Detail Report (CDR) report:New sharer joined the conference
Resolution
To fix this issue, install the April 2016 cumulative update 5.0.8308.956 for the Lync Server 2013, Core Components.
Workaround
To work around this issue, create a new meeting, and then let all the participants join the new one.