AttributeError processing template 'msg.idl.em': AttributeError: module 'em' has no attribute 'BUFFERED_OPT'

Question

When doing colcon build step in RealSense-ROS installation tutorial I face the CMake Error:

AttributeError: module 'em' has no attribute 'BUFFERED_OPT'

In my ros2_ws/src folder I have realsense-ros, vision_opencv, and xacro as the latter 2 caused errors of missing on rosdep install.

The software versions are:

• OS: Debian 12
• ROS distribution: Jazzy
• RealSense SDK: librealsense-2.47.0
• RealSense ROS wrapper: realsense-ros 3.2.2
• C compiler: GNU 12.2.0
• ament_cmake_ros: 0.12.0
• Python: 3.11.2
• em library: python3-empy 3.3.4-2

The full error log:

user@device:~/ros2_ws $ colcon build
Starting >>> cv_bridge
Starting >>> realsense2_camera_msgs
Starting >>> image_geometry
Starting >>> xacro
--- stderr: realsense2_camera_msgs
CMake Error at /opt/ros/jazzy/share/rosidl_adapter/cmake/rosidl_adapt_interfaces.cmake:57 (message):
 execute_process(/usr/bin/python3 -m rosidl_adapter --package-name
 realsense2_camera_msgs --arguments-file
 /home/pi/ros2_ws/build/realsense2_camera_msgs/rosidl_adapter__arguments__realsense2_camera_msgs.json
 --output-dir
 /home/pi/ros2_ws/build/realsense2_camera_msgs/rosidl_adapter/realsense2_camera_msgs
 --output-file
 /home/pi/ros2_ws/build/realsense2_camera_msgs/rosidl_adapter/realsense2_camera_msgs.idls)
 returned error code 1:
 AttributeError processing template 'msg.idl.em'
 Traceback (most recent call last):
 File "/opt/ros/jazzy/lib/python3.11/site-packages/rosidl_adapter/resource/__init__.py", line 51, in evaluate_template
 em.BUFFERED_OPT: True,
 ^^^^^^^^^^^^^^^
 AttributeError: module 'em' has no attribute 'BUFFERED_OPT'
 During handling of the above exception, another exception occurred:
 Traceback (most recent call last):
 File "<frozen runpy>", line 198, in _run_module_as_main
 File "<frozen runpy>", line 88, in _run_code
 File "/opt/ros/jazzy/lib/python3.11/site-packages/rosidl_adapter/__main__.py", line 19, in <module>
 sys.exit(main())
 ^^^^^^
 File "/opt/ros/jazzy/lib/python3.11/site-packages/rosidl_adapter/main.py", line 53, in main
 abs_idl_file = convert_to_idl(
 ^^^^^^^^^^^^^^^
 File "/opt/ros/jazzy/lib/python3.11/site-packages/rosidl_adapter/__init__.py", line 19, in convert_to_idl
 return convert_msg_to_idl(
 ^^^^^^^^^^^^^^^^^^^
 File "/opt/ros/jazzy/lib/python3.11/site-packages/rosidl_adapter/msg/__init__.py", line 39, in convert_msg_to_idl
 expand_template('msg.idl.em', data, output_file, encoding='iso-8859-1')
 File "/opt/ros/jazzy/lib/python3.11/site-packages/rosidl_adapter/resource/__init__.py", line 23, in expand_template
 content = evaluate_template(template_name, data)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 File "/opt/ros/jazzy/lib/python3.11/site-packages/rosidl_adapter/resource/__init__.py", line 69, in evaluate_template
 _interpreter.shutdown()
 ^^^^^^^^^^^^^^^^^^^^^
 AttributeError: 'NoneType' object has no attribute 'shutdown'
Call Stack (most recent call first):
 /opt/ros/jazzy/share/rosidl_cmake/cmake/rosidl_generate_interfaces.cmake:132 (rosidl_adapt_interfaces)
 CMakeLists.txt:22 (rosidl_generate_interfaces)
---
Failed <<< realsense2_camera_msgs [4.00s, exited with code 1]
Aborted <<< xacro [9.19s]
Aborted <<< image_geometry [1min 3s]
Aborted <<< cv_bridge [1min 51s]
Summary: 0 packages finished [1min 52s]
 1 package failed: realsense2_camera_msgs
 3 packages aborted: cv_bridge image_geometry xacro
 2 packages had stderr output: realsense2_camera_msgs xacro
 4 packages not processed

I tried:

• to update all versions and clean error logs, as descibed here
• to uninstall em and install empy instead, as described here, but with apt install python3-*

Nothing worked for me though. Thanks for any help in advance!

• Ali-AliAli-Ali: Here is the log for command colcon build --symlink-install --event-handlers console_cohesion+ --continue-on-error
• Ali-AliAli-Ali: Okay, it turned out that ROS2 didn't work properly, so the earlier steps of the tutorial may be the root of evil. But if there are any ideas other than that, I would appreciate them.

Answer 1

I faced the same issue, while trying colcon build, the source of the error is the incorrect version of empy, I fixed it by installing empy version 3.3.4 (pip install empy==3.3.4) for humble distro.

Hope this helps....

also, the conda environment can interfere with this, make sure to cross verify the conda environment using (which python3).