I just finished a support call dealing with this situation, so I thought it was worthy of a quick post. As my colleague, Jason Sloan, pointed out in his post “Lync Server 2010 to Lync Server 2013 Migration QoS Gotcha,” the Lync executable filename has changed from communicator.exe in Lync 2010 to lync.exe in Lync 2013. Jason brought up an excellent point about adjusting your QoS policies with the new executable name. The situation I just ran into is along the same lines, but this time dealing with an endpoint protection product.
My customer stated that they had recently begun installing the Lync 2013 client in preparation for an upgrade to Lync Server 2013. Everything was going well with the client installation until they noticed that Application Sharing, specifically Desktop Sharing was failing to connect. After a bit of discussion we remembered that their endpoint protection product required us to create an exception for the Lync 2010 client (communicator.exe). So, we decided that it made sense to create and test the same exception for the Lync 2013 client (lync.exe). After we put the exception in for lync.exe, Desktop Sharing was immediately successful.
So, the moral to the story is that when planning an upgrade of your Lync 2010 clients, be sure to include a discovery phase to uncover anything that may be directly referencing the Lync executable filename.