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Hello.
After installing turtlebot3 packages (Ubuntu 18.04, ROS melodic, following the instruction from here), roscore fails to run.
Following the traceback, I get the following error message:
File "/opt/ros/melodic/lib/python2.7/dist-packages/rosgraph_msgs/msg/_Log.py", line 8, in <module>
import std_msgs.msg
ImportError: No module named msg
How can I fix this error?
Thanks,
Arnon
It seems that the problem was with the Dropbox folder I used to store my catkin workspace.
After uninstalling ROS and Anaconda and staying with my previous workspace (in Dropbox), the problem still remained.
Only after deleting the workspace in Dropbox and building a new one outside, the problem was solved.
It seems that I will have to sync my work between home and office computers using other options, such as Git.
Thanks.
1st thought: did you source the setup.bash file after building? I'll assume yes, but do it if you didn't.
2nd thought: check this out: https://answers.ros.org/question/2716...
3rd thought: reinstall the module: sudo apt-get install --reinstall ros-melodic-std-msgs <-- or something like that
Hi Billy.
This is the response to the command: /home/lewinste/Dropbox/catkin_ws/src/std_msgs
If I understand correctly, the file _Log.py that raised the error can't find the module std_msg that contains the class msg. How can I make it search std_msgs that exists in catkin_ws/src?
I think that the path to std_msgs (that is /home/lewinste/Dropbox/catkin_ws/src) should be in the file sys.path (which I cannot find in my system).
When launching the Python command line and typing:
import sys
print(sys.path)
I get the following result:
['', '/home/lewinste/Dropbox/catkin_ws/devel/lib/python2.7/dist-packages', '/opt/ros/melodic/lib/python2.7/dist-packages', '/home/lewinste/anaconda3/lib/python37.zip', '/home/lewinste/anaconda3/lib/python3.7', '/home/lewinste/anaconda3/lib/python3.7/lib-dynload', '/home/lewinste/anaconda3/lib/python3.7/site-packages']
Again, no indication of the actual path where std_msgs can be found.
Any ideas? Thanks!
You appear to be using Anaconda. Please read this: Should we warn (new) users about difficulties with Python 3 and alternative Python interpreters? and the many Q&As about this here on ROS Answers.
Asked: 2019-10-08 17:21:54 -0500
Seen: 492 times
Last updated: Oct 10 '19
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