AttributeError: 'NoneType' object has no attribute 'release'

(logger) Traceback (most recent call last):
  File "/opt/nailgun/lib/python2.6/site-packages/web/application.py", line 239, in process
    return self.handle()
  File "/opt/nailgun/lib/python2.6/site-packages/web/application.py", line 230, in handle
    return self._delegate(fn, self.fvars, args)
  File "/opt/nailgun/lib/python2.6/site-packages/web/application.py", line 420, in _delegate
    return handle_class(cls)
  File "/opt/nailgun/lib/python2.6/site-packages/web/application.py", line 396, in handle_class
    return tocall(*args)
  File "<string>", line 2, in GET
  File "/opt/nailgun/lib/python2.6/site-packages/nailgun/api/handlers/base.py", line 55, in content_json
    data = func(*args, **kwargs)
  File "/opt/nailgun/lib/python2.6/site-packages/nailgun/api/handlers/disks.py", line 112, in GET
    volumes_info = DisksFormatConvertor.get_volumes_info(node)
  File "/opt/nailgun/lib/python2.6/site-packages/nailgun/volumes/manager.py", line 285, in get_volumes_info
    for space in get_node_spaces(node):
  File "/opt/nailgun/lib/python2.6/site-packages/nailgun/volumes/manager.py", line 88, in get_node_spaces
    role_mapping = node.cluster.release.volumes_metadata[
AttributeError: 'NoneType' object has no attribute 'release'