Cause and solution for failure to start ros2 after installing ISAAC SIM

Execution environment: Ubuntu 22.04.5 LTS, ROS2 humble

After installing ros2 and ISAAC SIM, if you try to start ros2 alone, it may fail to start because spdlog.so cannot be imported.

mizuki@mizuki-FRONTIER:~/PX4-Autopilot$ ros2

Traceback (most recent call last):

  File "/opt/ros/humble/bin/ros2", line 33, in <module>

    sys.exit(load_entry_point('ros2cli==0.18.11', 'console_scripts', 'ros2')())

  File "/opt/ros/humble/bin/ros2", line 25, in importlib_load_entry_point

    return next(matches).load()

  File "/usr/lib/python3.10/importlib/metadata/__init__.py", line 171, in load

    module = import_module(match.group('module'))

  File "/usr/lib/python3.10/importlib/__init__.py", line 126, in import_module

    return _bootstrap._gcd_import(name[level:], package, level)

  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import

  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load

  File "<frozen importlib._bootstrap>", line 1006, in _find_and_load_unlocked

  File "<frozen importlib._bootstrap>", line 688, in _load_unlocked

  File "<frozen importlib._bootstrap_external>", line 883, in exec_module

  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed

  File "/opt/ros/humble/lib/python3.10/site-packages/ros2cli/cli.py", line 22, in <module>

    from rclpy.executors import ExternalShutdownException

  File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/__init__.py", line 49, in <module>

    from rclpy.signals import install_signal_handlers

  File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/signals.py", line 15, in <module>

    from rclpy.exceptions import InvalidHandle

  File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/exceptions.py", line 15, in <module>

    from rclpy.impl.implementation_singleton import rclpy_implementation as _rclpy

  File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/impl/implementation_singleton.py", line 32, in <module>

    rclpy_implementation = import_c_library('._rclpy_pybind11', package)

  File "/opt/ros/humble/lib/python3.10/site-packages/rpyutils/import_c_library.py", line 39, in import_c_library

    return importlib.import_module(name, package=package)

  File "/usr/lib/python3.10/importlib/__init__.py", line 126, in import_module

    return _bootstrap._gcd_import(name[level:], package, level)

ImportError: /opt/ros/humble/lib/librcl_logging_spdlog.so: undefined symbol: _ZN6spdlog7details7log_msgC1ENS_10source_locEN3fmt2v817basic_string_viewIcEENS_5level10level_enumES6_

The C extension '/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/_rclpy_pybind11.cpython-310-x86_64-linux-gnu.so' failed to be imported while being present on the system. Please refer to 'https://docs.ros.org/en/{distro}/Guides/Installation-Troubleshooting.html#import-failing-even-with-library-present-on-the-system' for possible solutions

This error can occur when librcl_logging_spdlog.so is corrupted, so normally it would seem that simply reinstalling ros2 would solve the problem, but if ISAAC SIM is installed, the ROS2 bundled with ISAAC SIM (humble in this case) may be loaded first. If ISAAC SIM is corrupted, comment out the following line from ~.bashrc (the following line should exist if you followed the ISAAC SIM tutorial) to prevent the humble bundled with ISAAC SIM from being loaded, and then restart the terminal.

After that, you can enter the ros2 command without any errors and it will start normally.

The following example starts the ros2 listener for px4.