This page lists the changes that you must make in your code base in order to upgrade to the 2012.1.x releases.
The <GISettings><mcDepth> and <GISettings><mcMaxRayLength> settings are no longer read from the XML configuration file.
They are replaced by the new <mcMinDepth> and <mcMaxDepth> settings, which more closely reflect the global illumination method used by eRnsT.
If you currently use these settings in your XML file, you must update your configuration to use the new settings.