ROS melodic crash in controller_manager

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Hi everyone,

I recently set up my ros-melodic work environment (on Ubuntu) for a project and received the following error during controller switching in controller_manager:

Traceback (most recent call last):
File “/opt/ros/melodic/lib/controller_manager/spawner”, line 207, in
  if name == ‘main’: main()
File “/opt/ros/melodic/lib/controller_manager/spawner”, line 199, in main
  resp = switch_controller(loaded, , 2, False, 0.0)
File “/opt/ros/melodic/lib/python2.7/dist-packages/rospy/impl/tcpros_service.py”, line 439, in call
  return self.call(*args, **kwds)
File “/opt/ros/melodic/lib/python2.7/dist-packages/rospy/impl/tcpros_service.py”, line 495, in call
  request = rospy.msg.args_kwds_to_message(self.request_class, args, kwds)
File “/opt/ros/melodic/lib/python2.7/dist-packages/rospy/msg.py”, line 124, in args_kwds_to_message
  return data_class(*args)
File “/opt/ros/melodic/lib/python2.7/dist-packages/controller_manager_msgs/srv/_SwitchController.py”, line 59, in init
  super(SwitchControllerRequest, self).init(*args, **kwds)
File “/opt/ros/melodic/lib/python2.7/dist-packages/genpy/message.py”, line 301, in init
  raise TypeError(“Invalid number of arguments, args should be %s”%str(self.slots)+" args are"+str(args))
  TypeError: Invalid number of arguments, args should be [‘start_controllers’, ‘stop_controllers’, ‘strictness’] args are([‘joint_state_controller’, ‘PandaStatePublisher’], , 2, False, 0.0)

it seems that in line 199 of ‘/opt/ros/melodic/lib/controller_manager/spawner’ switch_control is called in the following manner:

resp = switch_controller(loaded, , 2, False, 0.0)

which causes the crash due to invalid number of arguments. I checked with a colleague that uses the same code and his version of ROS contains different inputs in that line. Could it be that some recent changes in ROS cause this crash? can anyone suggest some way to work around this?

Thanks!