When entering a command like 'openstack server list' or 'openstack --help' everything is working fine so it seems. When running the command 'openstack' it goes into this error state:

$ openstack --debug
START with options: ['--debug']
options: Namespace(access_token_endpoint='', auth_type='', auth_url='http://#.#.#.#:5000/v2.0', cacert='', client_id='', client_secret='', cloud='', debug=True, default_domain='default', deferred_help=False, domain_id='', domain_name='', endpoint='', identity_provider='', >  \identity_provider_url='', insecure=None, interface='', log_file=None, os_compute_api_version='', os_identity_api_version='', os_image_api_version='', os_network_api_version='', os_object_api_version='', os_project_id=None, os_project_name=None,                         >  \os_volume_api_version='', password='###', project_domain_id='', project_domain_name='', project_id='', project_name='admin', protocol='', region_name='RegionOne', scope='', service_provider_endpoint='', timing=False, token='', trust_id='', url='', user_domain_id='',   >  \user_domain_name='', user_id='', username='admin', verbose_level=3, verify=None)                                                                                                                                                                                             
defaults: {'secgroup_source': 'neutron', 'interface': None, 'api_timeout': None, 'compute_api_version': '2', 'orchestration_api_version': '1', 'auth_type': 'password', 'cert': None, 'floating_ip_source': 'neutron', 'network_api_version': '2', 'verify': True, 'cacert':     >  \None, 'dns_api_version': '2', 'disable_vendor_agent': {}, 'object_api_version': '1', 'database_api_version': '1.0', 'image_format': 'qcow2', 'volume_api_version': '1', 'image_api_use_tasks': False, 'key': None, 'baremetal_api_version': '1', 'image_api_version': '2',   >  \'identity_api_version': '2.0'}
cloud cfg: {'verbose_level': 3, 'interface': None, 'api_timeout': None, 'compute_api_version': '2', 'orchestration_api_version': '1', 'debug': True, 'auth_type': 'password', 'database_api_version': '1.0', 'auth': {'password': '###', 'project_name': 'admin', 'auth_url':    >  \'http://#.#.#.#:5000/v2.0', 'username': 'admin'}, 'deferred_help': False, 'floating_ip_source': 'neutron', 'cert': None, 'image_format': 'qcow2', 'network_api_version': '2', 'verify': True, 'cacert': None, 'dns_api_version': '2', 'disable_vendor_agent': {},            >  \'object_api_version': '1', 'region_name': 'RegionOne', 'default_domain': 'default', 'timing': False, 'secgroup_source': 'neutron', 'volume_api_version': '1', 'image_api_use_tasks': False, 'key': None, 'baremetal_api_version': '1', 'image_api_version': '2',             >  \'identity_api_version': '2.0'}
volume API version 1, cmd group openstack.volume.v1
network API version 2, cmd group openstack.network.v2
identity API version 2.0, cmd group openstack.identity.v2
image API version 2, cmd group openstack.image.v2
compute API version 2, cmd group openstack.compute.v2
object_store API version 1, cmd group openstack.object_store.v1
END return value: 1
Traceback (most recent call last):
  File "/usr/lib/python3.5/site-packages/openstackclient/shell.py", line 112, in run 
    ret_val = super(OpenStackShell, self).run(argv)
  File "/usr/lib/python3.5/site-packages/cliff/app.py", line 253, in run 
    result = self.interact()
  File "/usr/lib/python3.5/site-packages/cliff/app.py", line 292, in interact
    from .interactive import InteractiveApp
  File "/usr/lib/python3.5/site-packages/cliff/interactive.py", line 10, in <module>
    import cmd2
  File "/usr/lib/python3.5/site-packages/cmd2.py", line 187, in <module>
    if subprocess.mswindows:
AttributeError: module 'subprocess' has no attribute 'mswindows'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/bin/openstack", line 11, in <module>
    sys.exit(main())
  File "/usr/lib/python3.5/site-packages/openstackclient/shell.py", line 374, in main
    return OpenStackShell().run(argv)
  File "/usr/lib/python3.5/site-packages/openstackclient/shell.py", line 118, in run 
    self.log.error(traceback.format_exc(e))
  File "/usr/lib/python3.5/traceback.py", line 163, in format_exc
    return "".join(format_exception(*sys.exc_info(), limit=limit, chain=chain))
  File "/usr/lib/python3.5/traceback.py", line 117, in format_exception
    type(value), value, tb, limit=limit).format(chain=chain))
  File "/usr/lib/python3.5/traceback.py", line 464, in __init__
    capture_locals=capture_locals)
  File "/usr/lib/python3.5/traceback.py", line 322, in extract
    if limit >= 0:
TypeError: unorderable types: AttributeError() >= int()