Conferencing Modalities No Longer Function - MS16-065

Microsoft recently published a KB article related to a security bulletin MS16-065:

Symptoms

After you install the Microsoft .NET Framework Security Update MS16-065 on a Front End or Standard Edition server for Lync Server 2010, Lync Server 2013, or Skype for Business Server 2015, several conferencing modalities no longer function for internal users.

For a complete list of the .NET Framework updates that can cause this problem, see the Microsoft Security Bulletin MS16-065 - Important topic on the Microsoft TechNet website.

The following are known modalities affected by this issue:

·         Whiteboards

·         Uploading PowerPoint Presentations

·         Sharing Notes

·         Polls

·         Q&A

The error messages that users may receive when this problem occurs include the following:

·         We can’t connect to the server for presenting right now.

·         Network issues are keeping you from sharing notes and presenting whiteboards, polls and uploaded Pow…

·         An error occurred during the Skype Meeting.

I ran into this but it was not immediately apparent to which KB's this correlates to so I thought I would list out the ones that will cause this behavior and save someone else some time hunting:

Server 2008 R2:
KB3142024
KB3142033
KB3142037

Server 2012:
KB3142025
KB3142032
KB3142035

Server 2012 R2:
KB3142026
KB3142030
KB3142036

Update:

This also breaks the Lync Web App in Lync Server 2010 which is not documented in the KB at the time of this post. You will also need to add the following reg keys in [HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v2.0.50727\System.Net.ServicePointManager.SchSendAuxRecord]:

DWORD Name: C:\Program Files\Microsoft Lync Server 2010\OCSMCU\Web Meeting Conferencing\MeetingMCUSvc.exe
DWORD Value: 0

DWORD Name: C:\Windows\System32\inetsrv\w3wp.exe
DWORD Value: 0

Then restart the RTCMEETINGMCU service as well as perform an IISReset.