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rqt_publisher Segmentation Failure - ROS - kinetic

asked 2020-01-27 08:12:26 -0500

Vini71 gravatar image

updated 2020-01-27 13:53:42 -0500

Dirk Thomas gravatar image

Hi everyone, I am trying to execute rqt_publisher rqt_publisher command, however, it is not working. Detail: It is the only app (functionality) from rqt which is not working. I could not fix this issue alone. I tried to uninstall python libraries, reinstall ros-kinetic-desktop full, update and upgrade, but it still keeping the same error... I am using ROS-kinetic in ubuntu 16.04. The error is below:

Traceback (most recent call last):
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rqt_publisher/", line 105, in _update_thread_run
    message_class = roslib.message.get_message_class(base_type_str)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslib/", line 99, in get_message_class
    cls = genpy.message.get_message_class(message_type, reload_on_error=reload_on_error)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/genpy/", line 624, in get_message_class
    cls = _get_message_or_service_class('msg', message_type, reload_on_error=reload_on_error)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/genpy/", line 575, in _get_message_or_service_class
    pypkg = __import__('%s.%s' % (package, type_str))
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/autoware_map_msgs/msg/", line 7, in <module>
    from ._LaneChangeRelation import *
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/autoware_map_msgs/msg/", line 33
    None = 0
SyntaxError: cannot assign to None
QObject::~QObject: Timers cannot be stopped from another thread
Segmentation failuere (core image stored)


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This is unrelated to Autoware so please remove that tag.

Josh Whitley gravatar image Josh Whitley  ( 2020-01-27 15:15:58 -0500 )edit

Please see the answer below why the current problem is in the autoware package.

Dirk Thomas gravatar image Dirk Thomas  ( 2020-01-27 15:29:18 -0500 )edit

Aaaaaah, gotcha. Thanks for the clarification.

Josh Whitley gravatar image Josh Whitley  ( 2020-01-27 15:40:13 -0500 )edit

1 Answer

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answered 2020-01-27 13:53:25 -0500

Dirk Thomas gravatar image

The problem is in the last file of the stacktrace ( which contains the following line:

None = 0

Since None can't be assigned to in Python this code fails with a SyntaxError.

The reason is that the message definition uses Noneas the name of a constant which doesn't work in Python:

Since there is no automatic mangling to avoid the collision with language specific keywords I would suggest to file a ticket in the repo defining the message.

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Thanks @Dirk Thomas I did not know where to find the file you talked above in order to change the code... what I have done was removing all files which were installed regarding AUTOWARE. I did not remember that I have installed some plugins from Autoware...because my idea is working with it in the future, not now...but then...if I reinstall Autoware, am I going to have this issue again?

Vini71 gravatar image Vini71  ( 2020-01-28 09:44:03 -0500 )edit

Yes, until it gets fixed. Therefore I recommended to create an issue about this in that repo. Otherwise it is unlikely to be addressed.

Dirk Thomas gravatar image Dirk Thomas  ( 2020-01-28 10:03:05 -0500 )edit

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Asked: 2020-01-27 08:12:26 -0500

Seen: 205 times

Last updated: Jan 27 '20