To get straight to the point I want to know how to fix this error and understand it, what is an RLException? Why am I getting this? How can I avoid this later? Below I will post what I did step by step:

This is the directory where I have my files


This is the error i'm getting:

RLException: [ddrobot_rviz.launch] is neither a launch file in package [ros_robotics] nor is [ros_robotics] a launch file name
The traceback for the exception was written to the log file

The following are the codes for dd_robot.urdf and ddrobot_rviz.launch respectively:

<robot name="dd_robot">
    <!-- Base Link -->
    <link name ="base_link">
            <origin xyz = "0 0 0" rpy = "0 0 0" />
                <box size = ".5 .5 .25"/>
    <!-- values passed by command line input -->
    <arg name = "model" />
    <arg name = "gui" default ="False" />
    <!-- Set these parameters on Parameter Server -->
    <param name = "robot_description"
        textfile = "$(find ros_robotics)/urdf/$(arg model)" />
    <param name = "use_gui" value = "$(arg gui)" />
    <!-- Start 3 nodes: joint_state_publisher, robot_state_publisher
    rviz -->
    <node name = "joint_state_publisher" pkg = "joint_state_publisher"
            type = "joint_state_publisher" />
    <node name = "robot_state_publisher" pkg = "robot_state_publisher"
            type = "state_publisher" />
    <node name = "rviz" pkg = "rviz" type = "rviz" 
        args = "-d $(find ros_robotics)/urdf.rviz"
        required = "true" />

I do not yet completely understand what is written in the above codes, I'm following the ROS robotics by example book Fairchild.


1 Answer 1


I just had to re-enter:

source devel/setup.bash

In every new terminal.

  • 2
    $\begingroup$ Yes. Alternatively, you can add that line to your .bashrc file so you don't have to remember to source it in every new terminal. $\endgroup$
    – Ben
    Jun 29, 2020 at 16:42

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