Consider the following scenario:
You develop an application that creates one or more user endpoints by using Microsoft Lync Server 2010, Unified Communications Managed API 3.0 (UCMA 3.0).
One of the user endpoints uses a user account that is homed in a Microsoft Office Communications Server 2007 R2 environment.
The endpoint signs in, and you wait about 30 minutes.
In this scenario, the UCMA application encounters an unhandled NullReferenceException exception. Additionally, when you do not use an unhandled exception handler, the application crashes.
This issue occurs because of a protocol change in Lync Server 2010 and in UCMA 3.0. This change causes compatibility issues between Lync Server 2010, UCMA 3.0, and Office Communications Server 2007 R2. Therefore, an unhandled exception occurs when in-band provisioning data is updated.
To resolve this issue, install the following cumulative update:
2701655 Description of the cumulative update for Lync Server 2010, Unified Communications Managed API 3.0 Runtime: June 2012