In this case, a client complained that Arnold wasn’t rendering Yeti fur. I asked him to try with a simple sphere, and to send me the log (at verbosity level Warnings + Info).

This what I was looking for:

00:00:00  1222MB         | there are 1 light and 2 objects:
00:00:00  1222MB         |       1 persp_camera
00:00:00  1222MB         |       1 skydome_light
00:00:00  1222MB         |       1 utility
00:00:00  1222MB         |       1 lambert
00:00:00  1222MB         |       1 driver_exr
00:00:00  1222MB         |       1 gaussian_filter
00:00:00  1222MB         |       1 polymesh
00:00:00  1222MB         |       1 list_aggregate
00:00:00  1222MB         |       1 MayaShadingEngine
00:00:00  1222MB         |       1 renderview_display

So, what’s there? Well, the important thing is not what’s there, but what’s not there.

There’s no procedural. If Yeti was installed properly, there would a procedural node. The Yeti extension exports a procedural node when MtoA translates the scene.

That means the PATH or MTOA_EXTENSIONS_PATH wasn’t set up properly. I always use the Yeti module file for that.