ROS2 Troubleshooting

Some errors happens frequently when building ROS2 nodes. Here are a few ways to solve some errors

Cannot import name 'generate_py'

I often got the following error when I built packages that contains custom messages definitions :

Traceback (most recent call last):
  File "/opt/ros/humble/share/rosidl_generator_py/cmake/../../../lib/rosidl_generator_py/rosidl_generator_py", line 8, in <module>
    from rosidl_generator_py import generate_py
ImportError: cannot import name 'generate_py'

In the package's CMakeLists.txt, comment the following line:

find_package(rosidl_default_generators REQUIRED)
# find_package(rosidl_default_generators REQUIRED)

More about rosbags

There is an article about rosbags in ROS2 here