Maya 2016 Extension 2 introduces a new render setup system that provides a modern approach to creating render layers, collections and overrides. This new approach is intuitive and simplifies the management of complex scenes for rendering, and is now the recommended workflow.
You can continue to open your legacy scene files and use legacy render layers. However, you must first switch Maya to the Legacy Render Layers system. To do this, open the Preferences window, navigate to the Rendering category, then select Legacy Render Layers as the Preferred Render Setup system and restart Maya. The Legacy Render Layers system and the new Render Setup system are different and separate and cannot be used together. You can only use one or the other.
If you attempt to open, reference, or import a legacy scene file while your Preferred Render Setup system is set to Render Setup, errors would appear indicating that the combination of the two systems is not supported. Likewise, if you attempt to open, reference, or import a scene with Render Setup nodes while your Preferred Render Setup system is set to Legacy Render Layers, errors would also appear in the Script Editor.
Command line rendering
When performing command line rendering, you must ensure that your current Preferred Render Setup system matches the one that your scene file was saved with.
If you are not actively running Maya, your current Preferred Render Setup system is the one that you selected during your last Maya session.
For example, if you last run Maya in Legacy Render Layers mode, then attempt to use command line rendering to render a scene with render setup nodes, an error would occur indicating that this combination is not supported. The converse is also true, if you last run Maya in Render Setup mode, then attempt to use command line rendering to render a scene with legacy render layers, an error would occur.
To workaround this issue, launch Maya and select an alternate Preferred Render Setup system from the Preferences window.