Error with custom action in ros2 on R2025a Macbook 15.5

% Script to create ApplyTorque.action, TestMessage.msg, and run ros2genmsg with enhanced debugging

% Step 1: Define paths
customFolder = '/Users/xxxx/MATLAB/Projects/utilities/custom';
actionFolder = fullfile(customFolder, 'action');
msgFolder = fullfile(customFolder, 'msg');

% Create directories
if ~exist(customFolder, 'dir')
    mkdir(customFolder);
end
if ~exist(actionFolder, 'dir')
    mkdir(actionFolder);
end
if ~exist(msgFolder, 'dir')
    mkdir(msgFolder);
end

% Step 2: Create ApplyTorque.action
actionFilePath = fullfile(actionFolder, 'ApplyTorque.action');
actionContent = [
    '# Goal\n' ...
    'float64[6] torque\n' ...
    '\n' ...
    '---\n' ...
    '# Result\n' ...
    'bool success\n' ...
    '\n' ...
    '---\n' ...
    '# Feedback\n' ...
    'float64[6] positions\n'
];

fid = fopen(actionFilePath, 'w', 'n', 'UTF-8');
if fid == -1
    error('Cannot create file at %s', actionFilePath);
end
fprintf(fid, '%s', actionContent);
fclose(fid);

% Step 3: Create a test .msg file
msgFilePath = fullfile(msgFolder, 'TestMessage.msg');
msgContent = 'string name\nint32 age\n';
fid = fopen(msgFilePath, 'w', 'n', 'UTF-8');
if fid == -1
    error('Cannot create file at %s', msgFilePath);
end
fprintf(fid, '%s', msgContent);
fclose(fid);

% Step 4: Verify files and permissions
fprintf('Verifying folder structure:\n');
actionFiles = dir(fullfile(actionFolder, '*.action'));
msgFiles = dir(fullfile(msgFolder, '*.msg'));
if isempty(actionFiles)
    warning('No .action files found in %s', actionFolder);
else
    fprintf('Found .action file: %s\n', actionFiles(1).name);
end
if isempty(msgFiles)
    warning('No .msg files found in %s', msgFolder);
else
    fprintf('Found .msg file: %s\n', msgFiles(1).name);
end

% Check permissions
[status, attr] = fileattrib(customFolder);
if status && attr.UserRead && attr.UserWrite
    fprintf('Permissions OK for %s\n', customFolder);
else
    fprintf('Fixing permissions for %s\n', customFolder);
    system(['chmod -R u+rw ' customFolder]);
end

% Step 5: Display paths
fprintf('Action file created at: %s\n', actionFilePath);
fprintf('Message file created at: %s\n', msgFilePath);
fprintf('Folder path for ros2genmsg: %s\n', customFolder);

% Step 6: Validate ROS2 environment
fprintf('Checking ROS2 environment...\n');
try
    ros2('node', 'list'); % Test ROS2 connectivity
    fprintf('ROS2 environment appears accessible.\n');
catch
    warning('ROS2 environment not accessible. Please configure in Preferences > ROS Toolbox.\n');
end

% Step 7: Run ros2genmsg
fprintf('Attempting ros2genmsg with both .action and .msg files...\n');
try
    ros2genmsg(customFolder);
    fprintf('Successfully generated ROS2 message interfaces.\n');
catch e
    fprintf('Error running ros2genmsg: %s\n', e.message);
    fprintf('Debug: Trying with only .msg file...\n');
    % Temporarily move action folder
    tempActionFolder = fullfile(customFolder, 'action_temp');
    movefile(actionFolder, tempActionFolder);
    try
        ros2genmsg(customFolder);
        fprintf('Successfully generated .msg interfaces. Issue may be specific to .action files.\n');
    catch e2
        fprintf('Error with .msg only: %s\n', e2.message);
        fprintf('Debug: Check ROS2 environment in Preferences > ROS Toolbox and MATLAB/ROS2 compatibility.\n');
    end
    % Restore action folder
    movefile(tempActionFolder, actionFolder);
end

This is the output

Verifying folder structure:
Found .action file: ApplyTorque.action
Found .msg file: TestMessage.msg
Permissions OK for /Users/xxxx/MATLAB/Projects/utilities/custom
Action file created at: /Users/xxxx/MATLAB/Projects/utilities/custom/action/ApplyTorque.action
Message file created at: /Users/xxxx/MATLAB/Projects/utilities/custom/msg/TestMessage.msg
Folder path for ros2genmsg: /Users/xxxx/MATLAB/Projects/utilities/custom
Checking ROS2 environment...
ROS2 environment appears accessible.
Attempting ros2genmsg with both .action and .msg files...
Identifying message files in folder '/Users/xxxx/MATLAB/Projects/utilities/custom'..Done.
Error running ros2genmsg: Unable to find packages with '.msg' files, or '.srv' files, or '.action' files in /Users/xxxx/MATLAB/Projects/utilities/custom. Each message package must contain '.msg' files in a directory named 'msg', or '.srv' files in a directory named 'srv', or '.action' files in a directory named 'action', or a combination of any of these directories.
Debug: Trying with only .msg file...
Identifying message files in folder '/Users/xxxx/MATLAB/Projects/utilities/custom'..Done.
Error with .msg only: Unable to find packages with '.msg' files, or '.srv' files, or '.action' files in /Users/xxxx/MATLAB/Projects/utilities/custom. Each message package must contain '.msg' files in a directory named 'msg', or '.srv' files in a directory named 'srv', or '.action' files in a directory named 'action', or a combination of any of these directories.
Debug: Check ROS2 environment in Preferences > ROS Toolbox and MATLAB/ROS2 compatibility.

[Walter Roberson]

Someone recently reported a closely related error message against R2024b (apparently on Linux)

https://www.mathworks.com/matlabcentral/answers/2177875-ros2genmsg-not-recognizing-folder

[Carlos Javier]

You can see that the script creates the files.

Then it checks their existence

it is only the ros2genmsg that is creating the problem

[Walter Roberson]

I agree.

I wonder, though, whether it just might help to end customFolder with a / -- so asking it to look in /Users/xxxx/MATLAB/Projects/utilities/custom/ instead of in /Users/xxxx/MATLAB/Projects/utilities/custom . Just in case it is failing to put in the / itself when it is looking for the msg or action folders.

[Carlos Javier]

I did it both ways. I have also changed it in different locations. But it is still generating the same errors.

Answer 1

[Carlos Javier]

with the help of cursor and testing a lot i could solve it:

% Simple script to create ROS2 message and action files

% Create package directory structure
customFolder = fullfile(pwd, 'custom');
packageFolder = fullfile(customFolder, 'ultimate_msgs');  % Create ultimate_msgs package
actionFolder = fullfile(packageFolder, 'action');
msgFolder = fullfile(packageFolder, 'msg');

% Create directories
if ~exist(customFolder, 'dir')
    mkdir(customFolder);
end
if ~exist(packageFolder, 'dir')
    mkdir(packageFolder);
end
if ~exist(actionFolder, 'dir')
    mkdir(actionFolder);
end
if ~exist(msgFolder, 'dir')
    mkdir(msgFolder);
end

% Create package.xml (required for ROS2 package recognition)
packageXmlContent = sprintf(['<?xml version="1.0"?>\n' ...
    '<package format="3">\n' ...
    '  <name>ultimate_msgs</name>\n' ...
    '  <version>0.0.1</version>\n' ...
    '  <description>Custom messages and actions for ultimate robot arm</description>\n' ...
    '  <maintainer email="[e-mail]">Your Name</maintainer>\n' ...
    '  <license>BSD</license>\n\n' ...
    '  <buildtool_depend>ament_cmake</buildtool_depend>\n' ...
    '  <build_depend>rosidl_default_generators</build_depend>\n' ...
    '  <exec_depend>rosidl_default_runtime</exec_depend>\n' ...
    '  <member_of_group>rosidl_interface_packages</member_of_group>\n\n' ...
    '  <export>\n' ...
    '    <build_type>ament_cmake</build_type>\n' ...
    '  </export>\n' ...
    '</package>']);

fid = fopen(fullfile(packageFolder, 'package.xml'), 'w');
fprintf(fid, '%s', packageXmlContent);
fclose(fid);

% Create ApplyTorque.action
actionContent = sprintf('# Goal\nfloat64[6] torque\n---\n# Result\nbool success\n---\n# Feedback\nfloat64[6] positions');
fid = fopen(fullfile(actionFolder, 'ApplyTorque.action'), 'w');
fprintf(fid, '%s', actionContent);
fclose(fid);

% Create TestMessage.msg
msgContent = sprintf('string name\nint32 age');
fid = fopen(fullfile(msgFolder, 'TestMessage.msg'), 'w');
fprintf(fid, '%s', msgContent);
fclose(fid);

% Run ros2genmsg
try
    ros2genmsg(customFolder);  % Point to the parent folder containing ultimate_msgs
    disp('Successfully generated ROS2 message interfaces.');
catch ME
    fprintf('Error: %s\n', ME.message);
end

[Walter Roberson]

@Carlos Javier

It is not clear to me what the key change was?

I see that you moved the key files one more layer down in the hierarchy.

I see that you added a package.xml file.

I see that you corrected a mistake where before you wrote 'string name\nint32 age' to a file and now you sprintf() that first so that the \n are converted to newlines properly.

But none of these changes look significant? Was the major change adding the package.xml file ?