This error will occur when use autodiscover_task in celery and one of these app's folder did't have __init__.py file

pretty hard to find out what is going on.. debug information is lack

Traceback (most recent call last):
File "/opt/kibox/bin/celery", line 11, in
sys.exit(main())
File "/opt/kibox/local/lib/python3.4/site-packages/celery/main.py", line 30, in main
main()
File "/opt/kibox/local/lib/python3.4/site-packages/celery/bin/celery.py", line 81, in main
cmd.execute_from_commandline(argv)
File "/opt/kibox/local/lib/python3.4/site-packages/celery/bin/celery.py", line 770, in execute_from_commandline
super(CeleryCommand, self).execute_from_commandline(argv)))
File "/opt/kibox/local/lib/python3.4/site-packages/celery/bin/base.py", line 311, in execute_from_commandline
return self.handle_argv(self.prog_name, argv[1:])
File "/opt/kibox/local/lib/python3.4/site-packages/celery/bin/celery.py", line 762, in handle_argv
return self.execute(command, argv)
File "/opt/kibox/local/lib/python3.4/site-packages/celery/bin/celery.py", line 694, in execute
).run_from_argv(self.prog_name, argv[1:], command=argv[0])
File "/opt/kibox/local/lib/python3.4/site-packages/celery/bin/worker.py", line 179, in run_from_argv
return self(_args, *_options)
File "/opt/kibox/local/lib/python3.4/site-packages/celery/bin/base.py", line 274, in call
ret = self.run(_args, *_kwargs)
File "/opt/kibox/local/lib/python3.4/site-packages/celery/bin/worker.py", line 213, in run
).start()
File "/opt/kibox/local/lib/python3.4/site-packages/celery/worker/init.py", line 95, in init
self.app.loader.init_worker()
File "/opt/kibox/local/lib/python3.4/site-packages/celery/loaders/base.py", line 128, in init_worker
self.import_default_modules()
File "/opt/kibox/local/lib/python3.4/site-packages/celery/loaders/base.py", line 116, in import_default_modules
signals.import_modules.send(sender=self.app)
File "/opt/kibox/local/lib/python3.4/site-packages/celery/utils/dispatch/signal.py", line 166, in send
response = receiver(signal=self, sender=sender, *_named)
File "/opt/kibox/local/lib/python3.4/site-packages/amqp/utils.py", line 42, in call
self.set_error_state(exc)
File "/opt/kibox/local/lib/python3.4/site-packages/amqp/utils.py", line 39, in call
*_dict(self.kwargs, **kwargs) if self.kwargs else kwargs
File "/opt/kibox/local/lib/python3.4/site-packages/celery/app/base.py", line 330, in _autodiscover_tasks
self.loader.autodiscover_tasks(packages, related_name)
File "/opt/kibox/local/lib/python3.4/site-packages/celery/loaders/base.py", line 251, in autodiscover_tasks
related_name) if mod)
File "/opt/kibox/local/lib/python3.4/site-packages/celery/loaders/base.py", line 272, in autodiscover_tasks
return [find_related_module(pkg, related_name) for pkg in packages]
File "/opt/kibox/local/lib/python3.4/site-packages/celery/loaders/base.py", line 272, in
return [find_related_module(pkg, related_name) for pkg in packages]
File "/opt/kibox/local/lib/python3.4/site-packages/celery/loaders/base.py", line 294, in find_related_module
_imp.find_module(related_name, pkg_path)
File "/opt/kibox/lib/python3.4/imp.py", line 271, in find_module
"not {}".format(type(name)))
RuntimeError: 'list' must be None or a list, not <class 'str'>

the funny thing is that it was working fine, just kill the process kill -9 celery, as I have cast several times, but this time it stopped working

It is a common mistake, it is almost impossible to find, there is no solution?

a little help, know where to look.
vim /opt/kibox/lib/python3.4/imp.py
line: 271

Backwards-compatibilit

raise RuntimeError("'list' must be None or a list, "
"not {}".format(type(name)))

to

Backwards-compatibilit

print (path, list)
raise RuntimeError("'list' must be None or a list, "
"not {}".format(type(name)))

you will see something like
_NamespacePath(['/opt/kibox/kibox/apps/apprest']) <class 'list'>

rm /opt/kibox/kibox/apps/apprest/init.py

rm /opt/kibox/kibox/apps/apprest/init.pyc

touch /opt/kibox/kibox/apps/apprest/init.py

The development version (celery master branch) uses app,autodiscover_tasks() with an empty list instead of specifying INSTALLED_APPS, and the Django support populates it with apps.get_apps() instead, which may resolve the issue?

app.autodiscover_tasks (), if full app.autodiscover_tasks manually ([ "apps.example", "apps.example2"]), works perfect, app.autodiscover_tasks (settings.INSTALLED_APPS), also works well, app.autodiscover_tasks (lambda : settings.INSTALLED_APPS), works well,

The error detecting achieve, is that if one does not have my files, get the error.

apps / examples / *without py files .py

fails to get more information, lack of time and so far we could migrate to django 1.9

What's the status of this?

I am having the same problem with celery 4.0.1 and Django 1.10.1.

The issue is that Django allows namespace packages (see link in the OP), i.e. packages without __init__.py file, but celery's autodiscover_tasks fails on those packages with the error above.

I've tracked it down to the call of _imp.find_module here. imp.find_module is deprecated since Python 3.3.

I'm not sure what find_module is supposed to be doing that importlib.import_module can't do? Because when I replace the last bit of that code, starting from line 269, with

try:
    return importlib.import_module('{0}.{1}'.format(package, related_name))
 except ImportError:
    return

the loading seems to work fine for me. But as I said, I don't know what imp.find_module is supposed to be covering here (or why there's an import_module after that without catching ImportError), so I might be overlooking something.

I don't think you are overlooking anything here, @rbreu, so I'm creating a PR to fix this. And if the PR is rejected, at least we will have an explanation.