How to Delete Mental Ray Nodes in Maya

Heavy - Mental Ray nodes

Some animators are experiencing unexpected crashes in Maya, a problem which can be caused by legacy Mental Ray nodes being opened up in a version of Maya (2017 and up) which doesn't support Mental Ray.

For example, the Heavy rig, downloadable from creative crash, is a great rig for animating walk cycles and other actions. But, it does come with Mental Ray nodes, and this may cause Maya to crash unexpectedly.

Generally speaking, it's good housekeeping to delete any legacy Mental Ray nodes from your character rig when you open up Maya. 

So, how do you do this? Fortunately, the solution is a simple one.

How to delete Mental Ray nodes

The Problem

When you open a character rig created in a legacy version of Maya (ie 2016 and older), you a get a warning message about Mental Ray nodes: "Warning: This file contains Mental Ray nodes".

The existence of Mental Ray nodes can cause Maya to crash unexpectedly, since Mental Ray is no longer bundled with Maya - versions of Maya from 2017 onward have Arnold included as the primary ray-trace renderer.

The Solution

To remove this error message, and reduce the risk of crashes, the Mental Ray nodes will have to be deleted from the scene file.

You can do this by using the Optimize Scene Size Tool:
Navigate to File > Optimize Scene Size Tool option box [ ]
Scroll down and make sure "Unknown nodes" is checked on
Select Optimize

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