PyMEL is great. But…if pymel.log can’t be accessed, any plugin that uses PyMEL will fail to load.

And MtoA uses PyMEL, so every now and again I see a case where MtoA doesn’t load, and you get something like this in the script history:

import arnold
// Successfully imported python module 'arnold'
import mtoa
// Successfully imported python module 'mtoa'
import mtoa.cmds.registerArnoldRenderer;mtoa.cmds.registerArnoldRenderer.registerArnoldRenderer()
# Error: line 1: IOError: file C:\Program Files\Autodesk\Maya2016\bin\python27.zip\logging\__init__.py line 926: 13 #
// Error: Failed to register renderer 'arnold' //
// Error: line 1: initializePlugin function failed (mtoa) //

or this:

Error: line 1: IOError: file /Applications/Autodesk/maya2018/Maya.app/Contents/Frameworks/Python.framework/Versions/Current/lib/python2.7/logging/__init__.py line 935: 13

The important bit is this error:

# Error: line 1: IOError: file C:\Program Files\Autodesk\Maya2018\bin\python27.zip\logging\__init__.py

That error means that PyMELcannot create a log file in your user folder.

By default, the PyMEL log file is created in your Documents folder. For example, if your Windows user account name is Stephen, then this would be the log file:

C:\Users\Stephen\Documents\pymel.log

You need to check the permissions on that log file, or delete it so that PyMel can create a new log file.

Note that the pymel.log file may be a hidden file.