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ros2 param list: AttributeError: 'NoneType' object has no attribute 'result'

Why would something like this even happen? I would have thought "ros2 param list" should never throw an Exception no matter what but should give more descriptive errors instead.

In ROS1 "rosparam list" never throws exceptions like this. Is this a bug in ROS2?

$ ros2 node list                                                                                     
/foo_node
/link_ros2
$ ros2 param list /foo_node                                                                          
1632291581.817905 [0]    python3: using network interface wlp2s0 (udp/10.10.10.145) selected arbitrarily from: wlp2s0, docker0
Exception while calling service of node '/foo_node': None
Traceback (most recent call last):
  File "/opt/ros/galactic/bin/ros2", line 11, in <module>
    load_entry_point('ros2cli==0.13.1', 'console_scripts', 'ros2')()
  File "/opt/ros/galactic/lib/python3.8/site-packages/ros2cli/cli.py", line 67, in main
    rc = extension.main(parser=parser, args=args)
  File "/opt/ros/galactic/lib/python3.8/site-packages/ros2param/command/param.py", line 39, in main
    return extension.main(args=args)
  File "/opt/ros/galactic/lib/python3.8/site-packages/ros2param/verb/list.py", line 116, in main
    sorted_names = sorted(response.result.names)
AttributeError: 'NoneType' object has no attribute 'result'

Asked by dheeranet on 2021-09-22 01:21:02 UTC

Comments

Why would something like this even happen?

because it's software? Written by humans?

Edit: I've updated the title of your question, as "is broken" does not mean anything other than "it doesn't work".

Asked by gvdhoorn on 2021-09-22 02:35:14 UTC

I'm having the same issue with nav2_bt_navigator. On some of my robots, I get the error on the node itself, while on some others, I get that error on the navigate_through_poses_rclcpp_node plugin node.

I've not been able to dig much into this, would appreciate any insight on how to get more info.

Asked by po1 on 2023-02-10 14:42:32 UTC

Answers