When starting cinder [Kilo] on my machine the cinder-api is showing the following error:

/usr/lib/python2.7/site-packages/cinder/openstack/common/service.py:38: DeprecationWarning: The oslo namespace package is deprecated. Please use oslo_config instead.
  from oslo.config import cfg
2015-11-06 14:21:12.841 21801 CRITICAL cinder [-] IOError: [Errno 21] Is a directory: '/var/lib/cinder'
2015-11-06 14:21:12.841 21801 TRACE cinder Traceback (most recent call last):
2015-11-06 14:21:12.841 21801 TRACE cinder   File "/usr/bin/cinder-api", line 10, in <module>
2015-11-06 14:21:12.841 21801 TRACE cinder     sys.exit(main())
2015-11-06 14:21:12.841 21801 TRACE cinder   File "/usr/lib/python2.7/site-packages/cinder/cmd/api.py", line 56, in main
2015-11-06 14:21:12.841 21801 TRACE cinder     server = service.WSGIService('osapi_volume')
2015-11-06 14:21:12.841 21801 TRACE cinder   File "/usr/lib/python2.7/site-packages/cinder/service.py", line 341, in __init__
2015-11-06 14:21:12.841 21801 TRACE cinder     self.app = self.loader.load_app(name)
2015-11-06 14:21:12.841 21801 TRACE cinder   File "/usr/lib/python2.7/site-packages/cinder/wsgi.py", line 546, in load_app
2015-11-06 14:21:12.841 21801 TRACE cinder     return deploy.loadapp("config:%s" % self.config_path, name=name)
2015-11-06 14:21:12.841 21801 TRACE cinder   File "/usr/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 247, in loadapp
2015-11-06 14:21:12.841 21801 TRACE cinder     return loadobj(APP, uri, name=name, **kw)
2015-11-06 14:21:12.841 21801 TRACE cinder   File "/usr/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 271, in loadobj
2015-11-06 14:21:12.841 21801 TRACE cinder     global_conf=global_conf)
2015-11-06 14:21:12.841 21801 TRACE cinder   File "/usr/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 296, in loadcontext
2015-11-06 14:21:12.841 21801 TRACE cinder     global_conf=global_conf)
2015-11-06 14:21:12.841 21801 TRACE cinder   File "/usr/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 317, in _loadconfig
2015-11-06 14:21:12.841 21801 TRACE cinder     loader = ConfigLoader(path)
2015-11-06 14:21:12.841 21801 TRACE cinder   File "/usr/lib/python2.7/site-packages/paste/deploy/loadwsgi.py", line 393, in __init__
2015-11-06 14:21:12.841 21801 TRACE cinder     with open(filename) as f:
2015-11-06 14:21:12.841 21801 TRACE cinder IOError: [Errno 21] Is a directory: '/var/lib/cinder'
2015-11-06 14:21:12.841 21801 TRACE cinder

This then doesn't allow me to use any cinder commands showing the following error:

ERROR: Unable to establish connection to http://devstack-controller:8776/v1/b8ce94132b814473adb00a0659ae6b02/volumes/detail

What would be the best way to debug this issue?