bc@ubuntu:~$ roscore
Traceback (most recent call last):
File "/usr/bin/roscore", line 72, in <module>
import roslaunch
File "/usr/lib/python3/dist-packages/roslaunch/init.py", line 62, in <module>
from .scriptapi import ROSLaunch
File "/usr/lib/python3/dist-packages/roslaunch/scriptapi.py", line 42, in <module>
import roslaunch.parent
File "/usr/lib/python3/dist-packages/roslaunch/parent.py", line 54, in <module>
import roslaunch.server
File "/usr/lib/python3/dist-packages/roslaunch/server.py", line 79, in <module>
from rosgraph_msgs.msg import Log
ImportError: cannot import name 'Log' from 'rosgraph_msgs.msg' (/opt/ros/foxy/lib/python3.8/site-packages/rosgraph_msgs/msg/init.py)