ubuntu20.4中ros2版本，colcon build编译报错如下：

Starting >>> fishbot_navigation2
--- stderr: fishbot_navigation2                         
Traceback (most recent call last):
  File "/opt/ros/foxy/share/ament_cmake_core/cmake/core/package_xml_2_cmake.py", line 21, in <module>
    from catkin_pkg.package import parse_package_string
ModuleNotFoundError: No module named 'catkin_pkg'
CMake Error at /opt/ros/foxy/share/ament_cmake_core/cmake/core/ament_package_xml.cmake:94 (message):
  execute_process(/home/ros2/miniconda3/bin/python3
  /opt/ros/foxy/share/ament_cmake_core/cmake/core/package_xml_2_cmake.py
  /home/ros2/code/fishbot_ws/src/fishbot_navigation2/package.xml
  /home/ros2/code/fishbot_ws/build/fishbot_navigation2/ament_cmake_core/package.cmake)
  returned error code 1
Call Stack (most recent call first):
  /opt/ros/foxy/share/ament_cmake_core/cmake/core/ament_package_xml.cmake:49 (_ament_package_xml)
  /opt/ros/foxy/share/ament_lint_auto/cmake/ament_lint_auto_find_test_dependencies.cmake:31 (ament_package_xml)
  CMakeLists.txt:34 (ament_lint_auto_find_test_dependencies)


---
Failed   <<< fishbot_navigation2 [0.29s, exited with code 1]
                                
Summary: 0 packages finished [0.42s]
  1 package failed: fishbot_navigation2
  1 package had stderr output: fishbot_navigation2

解决方案如下：

pip3 install catkin_pkg

或者

pip install catkin_pkg