RQT Reconfigure - no plugin found

edit

I try to run:

rosrun rqt_reconfigure rqt_reconfigure

and I get:

CompositePluginProvider.discover() could not discover plugins from provider "<class 'rqt_gui.rospkg_plugin_provider.RospkgPluginProvider'>": 
Traceback (most recent call last):
  File "/opt/ros/hydro/lib/python2.7/dist-packages/qt_gui/composite_plugin_provider.py", line 58, in discover
    plugin_descriptors = plugin_provider.discover(discovery_data)
  File "/opt/ros/hydro/lib/python2.7/dist-packages/rqt_gui/ros_plugin_provider.py", line 65, in discover
    plugin_descriptors += self._parse_plugin_xml(package_name, plugin_xml)
  File "/opt/ros/hydro/lib/python2.7/dist-packages/rqt_gui/ros_plugin_provider.py", line 141, in _parse_plugin_xml
    module_name, class_from_class_type = attributes['class_type'].rsplit('.', 1)
ValueError: need more than 1 value to unpack

qt_gui_main() found no plugin matching "rqt_reconfigure"

How can I solve this?

EDIT:

rqt --list-plugins

returns:

CompositePluginProvider.discover() could not discover plugins from provider "<class 'rqt_gui.rospkg_plugin_provider.RospkgPluginProvider'>":
Traceback (most recent call last):
  File "/opt/ros/hydro/lib/python2.7/dist-packages/qt_gui/composite_plugin_provider.py", line 58, in discover
    plugin_descriptors = plugin_provider.discover(discovery_data)
  File "/opt/ros/hydro/lib/python2.7/dist-packages/rqt_gui/ros_plugin_provider.py", line 65, in discover
    plugin_descriptors += self._parse_plugin_xml(package_name, plugin_xml)
  File "/opt/ros/hydro/lib/python2.7/dist-packages/rqt_gui/ros_plugin_provider.py", line 141, in _parse_plugin_xml
    module_name, class_from_class_type = attributes['class_type'].rsplit('.', 1)
ValueError: need more than 1 value to unpack

rqt_dep.ros_pack_graph.RosPackGraph
rqt_image_view/ImageView
rqt_py_console.py_console.PyConsole
rqt_rviz/RViz
rqt_shell.shell.Shell
rqt_web.web.Web