Elevated CPU usage for Rtcsrv.exe process on a Lync Server 2010 front-end server

Applies to: Lync Server 2010 Enterprise EditionLync Server 2010 Standard Edition


On a Microsoft Lync Server 2010 front-end server, client users may experience the following symptoms:
  • New users cannot sign in to the front-end server.
  • Users cannot complete instant message conversations.
  • Users cannot join meetings that are hosted on the front-end server.
Additionally, the Front End (FE) service (Rtcsrv.exe) uses more CPU resources than expected.


This issue occurs because of a race condition in the rtcsrv.exe process.


To fix this issue, install the April, 2016 Cumulative Update 4.0.7577.728 for Lync Server 2010.