bpy.utils.previews error Hoping maybe a Blender dev can help with this. I have addons that load icons using the bpy.utils.previews module, but they give the following error

AttributeError: module 'bpy.utils' has no attribute 'previews'


The previews.py module exists in 2.7x/scripts/modules/bpy/utils. bpy.utils.previews only works for me in 2.78, not in 2.79 or 2.77/earlier.
It seems that the previews module must be explicitly imported to be found:

import bpy.utils.previews

should be placed at the start of the file.