Launch files not working on Ubuntu 20.04

[mkerklaan]

Hey all,

I'm trying to use the YDLidar on Ubuntu20.04 using ROS2. However, I keep getting the following error. I tried fixing it myself but I can't figure it out. I feel like it has something to do with using Ubuntu20.04 which builds differently somehow. You guys have any suggestions?

ros2 launch ydlidar_ros2_driver ydlidar_launch_view.py 
[INFO] [launch]: All log files can be found below /home/mkerklaan/.ros/log/2022-05-14-10-52-04-025192-mkerklaan-ThinkPad-T15-Gen-2i-603152
[INFO] [launch]: Default logging verbosity is set to INFO
Task exception was never retrieved
future: <Task finished name='Task-2' coro=<LaunchService._process_one_event() done, defined at /opt/ros/galactic/lib/python3.8/site-packages/launch/launch_service.py:226> exception=InvalidLaunchFileError('py')>
Traceback (most recent call last):
  File "/opt/ros/galactic/lib/python3.8/site-packages/launch/launch_description_sources/any_launch_file_utilities.py", line 53, in get_launch_description_from_any_launch_file
    return loader(launch_file_path)
  File "/opt/ros/galactic/lib/python3.8/site-packages/launch/launch_description_sources/python_launch_file_utilities.py", line 68, in get_launch_description_from_python_launch_file
    return getattr(launch_file_module, 'generate_launch_description')()
  File "/home/mkerklaan/Documents/GitRepos/YLidar/install/ydlidar_ros2_driver/share/ydlidar_ros2_driver/launch/ydlidar_launch_view.py", line 40, in generate_launch_description
    driver_node = LifecycleNode(
TypeError: __init__() missing 2 required keyword-only arguments: 'name' and 'namespace'

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/opt/ros/galactic/lib/python3.8/site-packages/launch/launch_service.py", line 228, in _process_one_event
    await self.__process_event(next_event)
  File "/opt/ros/galactic/lib/python3.8/site-packages/launch/launch_service.py", line 248, in __process_event
    visit_all_entities_and_collect_futures(entity, self.__context))
  File "/opt/ros/galactic/lib/python3.8/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
  File "/opt/ros/galactic/lib/python3.8/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
  File "/opt/ros/galactic/lib/python3.8/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 38, in visit_all_entities_and_collect_futures
    sub_entities = entity.visit(context)
  File "/opt/ros/galactic/lib/python3.8/site-packages/launch/action.py", line 108, in visit
    return self.execute(context)
  File "/opt/ros/galactic/lib/python3.8/site-packages/launch/actions/include_launch_description.py", line 130, in execute
    launch_description = self.__launch_description_source.get_launch_description(context)
  File "/opt/ros/galactic/lib/python3.8/site-packages/launch/launch_description_source.py", line 84, in get_launch_description
    self._get_launch_description(self.__expanded_location)
  File "/opt/ros/galactic/lib/python3.8/site-packages/launch/launch_description_sources/any_launch_description_source.py", line 53, in _get_launch_description
    return get_launch_description_from_any_launch_file(location)
  File "/opt/ros/galactic/lib/python3.8/site-packages/launch/launch_description_sources/any_launch_file_utilities.py", line 56, in get_launch_description_from_any_launch_file
    raise InvalidLaunchFileError(extension, likely_errors=exceptions)
launch.invalid_launch_file_error.InvalidLaunchFileError: Caught exception when trying to load file of format [py]: __init__() missing 2 required keyword-only arguments: 'name' and 'namespace'

[vik748]

+1 I am seeing the same error on ROS IRON, did you ever solve it?

[mkerklaan]

+1 I am seeing the same error on ROS IRON, did you ever solve it?

No, I never solved it. I moved on.

[vik748]

For those it might help, switching to the Humble branch resolved all the issues.