Animation Nodes 2.0 Reload (F8) Not Working I've downloaded the Windows prebuilt AN 2.0 and installed on Blender 2.78C. AN loads fine on startup and seems to work, but I am doing additional development and when I reload with F8, the following AN error is generated. 

Animation Nodes can't be reloaded.
Exception in module register(): 'E:\00visualNotes\workspace\visualNotes\addons\animation_nodes\__init__.py'
Traceback (most recent call last):
  File "C:\Program Files\Blender Foundation\Blender\2.78\scripts\modules\addon_utils.py", line 349, in enable
    mod.register()
  File "E:\00visualNotes\workspace\visualNotes\addons\animation_nodes__init__.py", line 176, in register
    bpy.utils.register_module(name)
  File "C:\Program Files\Blender Foundation\Blender\2.78\scripts\modules\bpy\utils__init__.py", line 618, in register_module
    raise Exception("register_module(%r): defines no classes" % module)
Exception: register_module('animation_nodes'): defines no classes

Any help with this would be greatly appreciated.
Animation Nodes 2.0 does not support reloading.

This is because Python does not support reloading of extension modules, which AN has a lot of since it uses Cython.

So unfortunately you will have to disable AN completely during development or restart Blender every time you make a change.