Cherrypy - ImportError: No module named 'winreg'

When starting up Cherrypy (on Ubuntu 14.04, using Python 3) I get the following error (shown in my Python console):

[04/Sep/2014:22:14:20] ENGINE Started monitor thread '_TimeoutMonitor'.
    [04/Sep/2014:22:14:20] ENGINE Started monitor thread 'Autoreloader'.
    [04/Sep/2014:22:14:20] ENGINE Serving on
    [04/Sep/2014:22:14:20] ENGINE Bus STARTED
    [04/Sep/2014:22:14:21] ENGINE Error in background task thread function <bound method of 
<cherrypy.process.plugins.Autoreloader object at 0x7fe28413e208>>.
    Traceback (most recent call last):
      File "/usr/local/lib/python3.4/dist-packages/cherrypy/process/", line 500, in run
        self.function(*self.args, **self.kwargs)
      File "/usr/local/lib/python3.4/dist-packages/cherrypy/process/", line 632, in run
        for filename in self.sysfiles() | self.files:
      File "/usr/local/lib/python3.4/dist-packages/cherrypy/process/", line 616, in sysfiles
        hasattr(m, '__loader__') and
      File "/usr/lib/python3/dist-packages/", line 116, in __getattr__
        _module = self._resolve()
      File "/usr/lib/python3/dist-packages/", line 105, in _resolve
        return _import_module(self.mod)
      File "/usr/lib/python3/dist-packages/", line 76, in _import_module
    ImportError: No module named 'winreg'

Since Winreg is a Windows-specific module (used for accessing the registry), Six (a Python 2 to 3 compatibility module) probably shouldn't try to load it under Linux.

Looking in, I see the following:

def __getattr__(self, attr):
        # Hack around the Django autoreloader. The reloader tries to get
        # __file__ or __name__ of every module in sys.modules. This doesn't work
        # well if this MovedModule is for an module that is unavailable on this
        # machine (like winreg on Unix systems). Thus, we pretend __file__ and
        # __name__ don't exist if the module hasn't been loaded yet. See issues
        # #51 and #53.
        if attr in ("__file__", "__name__") and self.mod not in sys.modules:
            raise AttributeError
        _module = self._resolve()
        value = getattr(_module, attr)
        setattr(self, attr, value)
        return value

From the comment above: This doesn't work well if this MovedModule is for a module that is unavailable on this machine (like winreg on Unix systems)

Since the stack trace indicates that this exception is occurring in the AutoReloader functionality, and I don't need that functionality, I just disabled it by adding:

'engine.autoreload_on': False

as follows:

from controllers import MyController
import cherrypy

if __name__ == '__main__':
    server_config = {
        'server.socket_host': '',
        'server.socket_port': 60000,
        'engine.autoreload_on': False

    cherrypy.tree.mount(MyController(), '/Home', {})

and now the exception is not thrown.


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