ROS fails to launch on remote with the exception: No existing session

asked 2019-11-08 13:49:50 -0600

bbuyukkucak gravatar image

Hi all,

Master: OS: Ubuntu 18.04.3 LTS Kernel: Linux 5.0.0-32 and ROS Melodic

Remote: OS: Ubuntu 18.04.2 LTS Kernel:Linux 4.15.0-1032-raspi2 and ROS Melodic

I have verified that ROS_MASTER_URI and ROS_IP are correctly set in both machines and I am able run nodes from the remote, however when I try to launch the remote node from the master machine with a launch file, I receive this error in verbose mode.

    roslaunch smart_model display_model.launch target:=true -vvv

... logging to /home/syn-robotics/.ros/log/18323244-0017-11ea-9b86-100c0009d566/roslaunch-synrobotics-10161.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

... loading XML file [/opt/ros/melodic/etc/ros/roscore.xml]
... executing command param [rosversion roslaunch]
Added parameter [/rosversion]
... executing command param [rosversion -d]
Added parameter [/rosdistro]
Added core node of type [rosout/rosout] in namespace [/]
... loading XML file [/home/syn-robotics/catkin_ws/src/smart_model/launch/display_model.launch]
Added node of type [smart_model/] in namespace [/]
Added parameter [/joint_state_publisher/source_list]
Added node of type [joint_state_publisher/joint_state_publisher] in namespace [/]
Added node of type [robot_state_publisher/state_publisher] in namespace [/]
Added parameter [/robot_description]
Added machine [raspberry]
Added node of type [robot_arm/] in namespace [/]
started roslaunch server
remote[] starting roslaunch
remote[]: creating ssh connection to
remote[]: failed to launch on raspberry:

Unable to establish ssh connection to []: No existing session

[] killing on exit
RLException: unable to start remote roslaunch child:
The traceback for the exception was written to the log file

I am able to ssh into the remote machine with no problem, and no password. I generated a key and copied into the remote with copy-id, by following this tutorial.

This is my launch-file:


  <arg name="model" default="$(find smart_model)/urdf/smart_model.urdf"/>
  <arg name="rvizconfig" default="$(find smart_model)/rviz/smart_model.rviz" />
  <arg name="interactive" default="false"/>
  <arg name="target" default="false"/>

  <node if="$(arg interactive)" name="smart_marker" pkg="smart_model" type="" output="screen"/>
  <!-- <node if="$(arg target)" name="target_marker" pkg="smart_model" type="" output="screen"/> -->
  <node if="$(arg target)" name="move_to_target" pkg="smart_model" type="" output="screen"/>

  <node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher">
    <rosparam param="source_list">[ik_joint_states] </rosparam>
    <!-- <param name="use_gui" value="true"/> -->
  <node name="robot_state_publisher" pkg="robot_state_publisher" type="state_publisher" />

  <node if="$(arg interactive)" name="rviz" pkg="rviz" type="rviz" args="-d $(arg rvizconfig)" required="true" />
  <param name="robot_description" textfile="$(arg model)"/>

  <machine name="raspberry" address="" default="true" env-loader="/home/pi/catkin_ws/devel/"/>
  <node machine="raspberry" pkg="robot_arm" name="smart_interface" type=""/>


And finally, this is my environment loader file:


export ...
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not sure this is the cause, but in any case this is not a valid ROS_MASTER_URI.

It should probably be:


or similar.

gvdhoorn gravatar image gvdhoorn  ( 2019-11-08 15:39:22 -0600 )edit

Hi, thank you for your response but I don't think that fixes the problem. I updated the environment loader but that didn't fix it.

bbuyukkucak gravatar image bbuyukkucak  ( 2019-11-12 11:34:24 -0600 )edit

Isn't there anyone who can address this problem? Can you please suggest maybe a different place that I can post this question?

bbuyukkucak gravatar image bbuyukkucak  ( 2019-11-21 12:47:07 -0600 )edit