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colcon build --symlink-install: TypeError: 'NoneType' object is not iterable

asked 2020-03-09 03:48:43 -0500

AHJL001 gravatar image

updated 2020-03-09 03:59:20 -0500

gvdhoorn gravatar image

Hi, I am trying to install ROS 2 on my ubuntu 18.04 laptop.

However, after entering colcon build --symlink-install. I am met with this error,

Starting >>> test_launch_ros
--- stderr: test_launch_ros                     
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/colcon_core/executor/", line 91, in __call__
    rc = await self.task(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/colcon_core/task/", line 92, in __call__
    return await task_method(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/colcon_ros/task/ament_python/", line 55, in build
    setup_py_data.get('data_files', []))
  File "/usr/lib/python3/dist-packages/colcon_core/task/python/", line 34, in get_data_files_mapping
    for data_file in data_files:
TypeError: 'NoneType' object is not iterable
Failed   <<< test_launch_ros    [ Exited with code 1 ]
Aborted  <<< examples_rclcpp_minimal_action_server         
Aborted  <<< test_communication                           
Aborted  <<< message_filters                             
Aborted  <<< examples_rclcpp_minimal_composition         
Aborted  <<< examples_rclcpp_minimal_action_client       
Aborted  <<< rosbag2                                     
Aborted  <<< quality_of_service_demo_cpp                  
Aborted  <<< intra_process_demo                           
Aborted  <<< demo_nodes_cpp                               
Aborted  <<< test_quality_of_service                      
Aborted  <<< turtlesim


Summary: 220 packages finished [2min 23s]
  1 package failed: test_launch_ros
  11 packages aborted: demo_nodes_cpp examples_rclcpp_minimal_action_client examples_rclcpp_minimal_action_server examples_rclcpp_minimal_composition intra_process_demo message_filters quality_of_service_demo_cpp rosbag2 test_communication test_quality_of_service turtlesim
  1 package had stderr output: test_launch_ros
  39 packages not processed
'NoneType' object is not iterable

Please advise, thank you.

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1 Answer

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answered 2020-03-09 04:21:31 -0500

marguedas gravatar image

Based on this error, I'm guessing you're trying to build ROS 2 Dashing from source (despite the question being tagged melodic). Note that if you build the last distro: ROS Eloquent, you won't face the issue.

Can you confirm the version of colcon-ros you are using (you can run colcon version-check) ? How did you install colcon ?

It seems that some versions of colcon-ros had a bug in that regard that has been recently fixed. To get the fix you need to be using colcon-ros 0.3.17, that is currently only available from pip, the deb version hasn't hit the main repository yet.

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This was it! Merci beaucoup!

AHJL001 gravatar image AHJL001  ( 2020-03-09 21:27:51 -0500 )edit

$ colcon version-check colcon-ros 0.3.16: newer version available (0.3.17)

How can i upgrade colcon-ros fot 0.3.16 --> 0.3.17

komkrit gravatar image komkrit  ( 2020-03-09 23:08:11 -0500 )edit

currently you either need to install it via pip:

pip3 install colcon-common-extensions

or to install the package from the testing repository:

sudo sh -c 'echo "deb [arch=amd64,arm64] `lsb_release -cs` main" > /etc/apt/sources.list.d/ros2-testing.list'
sudo apt update
sudo apt upgrade python3-colcon-ros
marguedas gravatar image marguedas  ( 2020-03-10 04:38:36 -0500 )edit

You shouldn't install Python packages via pip if there are Debian packages for it. The Debian package should be in the main repo by now - so there shouldn't be a need to switch to the testing repo.

Dirk Thomas gravatar image Dirk Thomas  ( 2020-03-10 13:10:04 -0500 )edit

Thank you so much merduedas... _/|_

komkrit gravatar image komkrit  ( 2020-03-11 06:25:15 -0500 )edit

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Asked: 2020-03-09 03:48:43 -0500

Seen: 983 times

Last updated: Mar 09 '20