# ROS2-UXRCE Agent-Can't Subscribe to published topics

**URL:** <https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734>\
**Category:** ROS 1 / ROS 2\
**Created:** [December 9, 2023, 6:04am UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734 "2023-12-09T06:04:29Z")\
**Posts on this page:** 16\
**Page:** 1

<div class="post-metadata">

**Author:** ![Gradle](https://discuss.px4.io/user_avatar/discuss.px4.io/gradle/32/14171_2.png) [@Gradle](https://discuss.px4.io/u/Gradle)\
**Post date:** [December 9, 2023, 6:04am UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/1 "2023-12-09T06:04:29Z")

</div>

Hi, I have been trying to connect my Cube Orange(uxrce\_dds\_client start -t serial -d /dev/ttyS2 -b 921600) with RPI running UBUNTU 22.04 (HUMBLE). I followed the following documentation -  
[https://docs.px4.io/main/en/companion\_computer/pixhawk\_rpi.html](https://docs.px4.io/main/en/companion_computer/pixhawk_rpi.html)  
Successfully created publisher and also i am able to list the ros topics-

```auto
/fmu/in/obstacle_distance
/fmu/in/offboard_control_mode
/fmu/in/onboard_computer_status
/fmu/in/sensor_optical_flow
/fmu/in/telemetry_status
/fmu/in/trajectory_setpoint
/fmu/in/vehicle_attitude_setpoint
/fmu/in/vehicle_command
/fmu/in/vehicle_mocap_odometry
/fmu/in/vehicle_rates_setpoint
/fmu/in/vehicle_trajectory_bezier
/fmu/in/vehicle_trajectory_waypoint
/fmu/in/vehicle_visual_odometry
/fmu/out/failsafe_flags
/fmu/out/position_setpoint_triplet
/fmu/out/sensor_combined
/fmu/out/timesync_status
/fmu/out/vehicle_attitude
/fmu/out/vehicle_control_mode
/fmu/out/vehicle_local_position
/fmu/out/vehicle_odometry
/fmu/out/vehicle_status
/parameter_events
/rosout

```

After which when I try to echo topics (ros2 topic echo /fmu/out/vehicle)  
I get blank screen and after 2-3 times of trying following error pops up-

```auto
kds-ros@kdsros-desktop:~/ws_sensor_combined$ ros2 topic echo /fmu/out/vehicle_status
2023-12-09 10:58:07.540 [RTPS_TRANSPORT_SHM Error] Failed init_port fastrtps_port7419: open_and_lock_file failed -> Function open_port_internal

```

On my mavlink console when the Agent start there is activity on the mavlink console.

i am also attaching the out for

> ros2 doctor report

```auto
kds-ros@kdsros-desktop:~/ws_sensor_combined$ ros2 doctor --report
2023-12-09 11:08:05.961 [RTPS_TRANSPORT_SHM Error] Failed init_port fastrtps_port7419: open_and_lock_file failed -> Function open_port_internal

   NETWORK CONFIGURATION
inet : 127.0.0.1
inet4 : ['127.0.0.1']
inet6 : ['::1']
netmask : 255.0.0.0
device : lo
flags : 73<RUNNING,LOOPBACK,UP>
mtu : 65536
inet : 192.168.1.9
inet4 : ['192.168.1.9']
ether : d8:3a:dd:88:cb:9b
inet6 : ['fe80::4182:1f25:cc6e:19ef%wlan0']
netmask : 255.255.255.0
device : wlan0
flags : 4163<BROADCAST,RUNNING,MULTICAST,UP>
mtu : 1500
broadcast : 192.168.1.255
ether : d8:3a:dd:88:cb:9a
device : eth0
flags : 4099<BROADCAST,MULTICAST,UP>
mtu : 1500

   PACKAGE VERSIONS
px4_ros_com : latest=, local=0.1.0
px4_msgs : latest=, local=2.0.1
rosidl_runtime_c : latest=3.1.5, local=3.1.5
pendulum_msgs : latest=0.20.3, local=0.20.3
rosidl_typesupport_c : latest=2.0.1, local=2.0.1
composition_interfaces : latest=1.2.1, local=1.2.1
examples_rclpy_minimal_client : latest=0.15.1, local=0.15.1
pendulum_control : latest=0.20.3, local=0.20.3
kdl_parser : latest=2.6.4, local=2.6.4
ament_lint : latest=0.12.9, local=0.12.9
unique_identifier_msgs : latest=2.2.1, local=2.2.1
rcl_interfaces : latest=1.2.1, local=1.2.1
geometry2 : latest=0.25.5, local=0.25.5
examples_rclcpp_minimal_action_client : latest=0.15.1, local=0.15.1
ros2service : latest=0.18.7, local=0.18.7
shared_queues_vendor : latest=0.15.8, local=0.15.8
tf2_bullet : latest=0.25.5, local=0.25.5
tf2_msgs : latest=0.25.5, local=0.25.5
ament_cmake_ros : latest=0.10.0, local=0.10.0
demo_nodes_cpp : latest=0.20.3, local=0.20.3
ros_base : latest=0.10.0, local=0.10.0
rosbag2_cpp : latest=0.15.8, local=0.15.8
python_qt_binding : latest=1.1.2, local=1.1.2
ament_cmake_include_directories : latest=1.3.6, local=1.3.6
rqt_shell : latest=1.0.2, local=1.0.2
image_transport : latest=3.1.7, local=3.1.7
sensor_msgs_py : latest=4.2.3, local=4.2.3
std_srvs : latest=4.2.3, local=4.2.3
rqt_gui : latest=1.1.5, local=1.1.5
rqt_topic : latest=1.5.0, local=1.5.0
ament_cmake_export_include_directories : latest=1.3.6, local=1.3.6
rclpy : latest=3.3.11, local=3.3.11
action_msgs : latest=1.2.1, local=1.2.1
rosbag2_transport : latest=0.15.8, local=0.15.8
ament_xmllint : latest=0.12.9, local=0.12.9
nav_msgs : latest=4.2.3, local=4.2.3
rosbag2_py : latest=0.15.8, local=0.15.8
angles : latest=1.15.0, local=1.15.0
ros2cli_common_extensions : latest=0.1.1, local=0.1.1
ament_cmake_uncrustify : latest=0.12.9, local=0.12.9
rmw_fastrtps_cpp : latest=6.2.5, local=6.2.5
rosidl_generator_cpp : latest=3.1.5, local=3.1.5
urdf : latest=2.6.0, local=2.6.0
examples_rclcpp_minimal_publisher : latest=0.15.1, local=0.15.1
visualization_msgs : latest=4.2.3, local=4.2.3
ament_cpplint : latest=0.12.9, local=0.12.9
std_msgs : latest=4.2.3, local=4.2.3
ros2doctor : latest=0.18.7, local=0.18.7
turtlesim : latest=1.4.2, local=1.4.2
rviz_assimp_vendor : latest=11.2.9, local=11.2.9
rqt_srv : latest=1.0.3, local=1.0.3
rcutils : latest=5.1.4, local=5.1.4
rcl_logging_spdlog : latest=2.3.1, local=2.3.1
ament_flake8 : latest=0.12.9, local=0.12.9
ament_cmake_gtest : latest=1.3.6, local=1.3.6
tf2_eigen : latest=0.25.5, local=0.25.5
rosidl_cli : latest=3.1.5, local=3.1.5
rcl_lifecycle : latest=5.3.6, local=5.3.6
examples_rclpy_minimal_action_client : latest=0.15.1, local=0.15.1
geometry_msgs : latest=4.2.3, local=4.2.3
rqt_common_plugins : latest=1.2.0, local=1.2.0
ament_index_cpp : latest=1.4.0, local=1.4.0
fastrtps_cmake_module : latest=2.2.2, local=2.2.2
ros2action : latest=0.18.7, local=0.18.7
pluginlib : latest=5.1.0, local=5.1.0
sros2 : latest=0.10.4, local=0.10.4
tf2_ros_py : latest=0.25.5, local=0.25.5
rosidl_runtime_py : latest=0.9.3, local=0.9.3
ros2lifecycle : latest=0.18.7, local=0.18.7
ament_cmake_export_libraries : latest=1.3.6, local=1.3.6
rmw : latest=6.1.1, local=6.1.1
laser_geometry : latest=2.4.0, local=2.4.0
ros2node : latest=0.18.7, local=0.18.7
ament_cmake_pep257 : latest=0.12.9, local=0.12.9
launch_testing_ament_cmake : latest=1.0.4, local=1.0.4
ros_environment : latest=3.2.2, local=3.2.2
rcl_action : latest=5.3.6, local=5.3.6
ros2cli : latest=0.18.7, local=0.18.7
pcl_msgs : latest=1.0.0, local=1.0.0
tlsf : latest=0.7.0, local=0.7.0
rclcpp_components : latest=16.0.7, local=16.0.7
qt_gui_cpp : latest=2.2.2, local=2.2.2
rclcpp_lifecycle : latest=16.0.7, local=16.0.7
osrf_pycommon : latest=2.0.2, local=2.0.2
ament_lint_auto : latest=0.12.9, local=0.12.9
rviz_default_plugins : latest=11.2.9, local=11.2.9
rviz_rendering : latest=11.2.9, local=11.2.9
interactive_markers : latest=2.3.2, local=2.3.2
joy : latest=3.3.0, local=3.3.0
rqt_msg : latest=1.2.0, local=1.2.0
rqt_service_caller : latest=1.0.5, local=1.0.5
tracetools : latest=4.1.1, local=4.1.1
ament_cmake_lint_cmake : latest=0.12.9, local=0.12.9
statistics_msgs : latest=1.2.1, local=1.2.1
tf2_ros : latest=0.25.5, local=0.25.5
ros2bag : latest=0.15.8, local=0.15.8
rcpputils : latest=2.4.1, local=2.4.1
tf2_py : latest=0.25.5, local=0.25.5
rviz_ogre_vendor : latest=11.2.9, local=11.2.9
ament_index_python : latest=1.4.0, local=1.4.0
rcl_yaml_param_parser : latest=5.3.6, local=5.3.6
teleop_twist_joy : latest=2.4.5, local=2.4.5
qt_dotgraph : latest=2.2.2, local=2.2.2
ros2param : latest=0.18.7, local=0.18.7
stereo_msgs : latest=4.2.3, local=4.2.3
diagnostic_msgs : latest=4.2.3, local=4.2.3
tango_icons_vendor : latest=0.1.1, local=0.1.1
ament_cmake_pytest : latest=1.3.6, local=1.3.6
tf2_kdl : latest=0.25.5, local=0.25.5
tlsf_cpp : latest=0.13.0, local=0.13.0
rosbag2_interfaces : latest=0.15.8, local=0.15.8
rosidl_runtime_cpp : latest=3.1.5, local=3.1.5
examples_rclcpp_minimal_service : latest=0.15.1, local=0.15.1
tinyxml2_vendor : latest=0.7.6, local=0.7.6
launch_xml : latest=1.0.4, local=1.0.4
zstd_vendor : latest=0.15.8, local=0.15.8
logging_demo : latest=0.20.3, local=0.20.3
rosbag2_compression : latest=0.15.8, local=0.15.8
ament_cmake_auto : latest=1.3.6, local=1.3.6
rosbag2_compression_zstd : latest=0.15.8, local=0.15.8
rqt_action : latest=2.0.1, local=2.0.1
rpyutils : latest=0.2.1, local=0.2.1
launch_testing : latest=1.0.4, local=1.0.4
rosidl_cmake : latest=3.1.5, local=3.1.5
rqt_py_common : latest=1.1.5, local=1.1.5
dummy_sensors : latest=0.20.3, local=0.20.3
libcurl_vendor : latest=3.1.1, local=3.1.1
ament_uncrustify : latest=0.12.9, local=0.12.9
examples_rclpy_minimal_service : latest=0.15.1, local=0.15.1
trajectory_msgs : latest=4.2.3, local=4.2.3
image_geometry : latest=3.2.1, local=3.2.1
examples_rclcpp_multithreaded_executor : latest=0.15.1, local=0.15.1
sros2_cmake : latest=0.10.4, local=0.10.4
ros2pkg : latest=0.18.7, local=0.18.7
pcl_conversions : latest=2.4.0, local=2.4.0
cv_bridge : latest=3.2.1, local=3.2.1
ament_cmake_export_interfaces : latest=1.3.6, local=1.3.6
rosidl_generator_py : latest=0.14.4, local=0.14.4
ament_cmake_export_dependencies : latest=1.3.6, local=1.3.6
rclcpp_action : latest=16.0.7, local=16.0.7
libyaml_vendor : latest=1.2.2, local=1.2.2
ament_lint_common : latest=0.12.9, local=0.12.9
launch_ros : latest=0.19.6, local=0.19.6
domain_coordinator : latest=0.10.0, local=0.10.0
keyboard_handler : latest=0.0.5, local=0.0.5
rqt_console : latest=2.0.2, local=2.0.2
ament_cmake_export_link_flags : latest=1.3.6, local=1.3.6
rosidl_typesupport_cpp : latest=2.0.1, local=2.0.1
ament_cmake_gmock : latest=1.3.6, local=1.3.6
message_filters : latest=4.3.3, local=4.3.3
intra_process_demo : latest=0.20.3, local=0.20.3
topic_monitor : latest=0.20.3, local=0.20.3
yaml_cpp_vendor : latest=8.0.2, local=8.0.2
spdlog_vendor : latest=1.3.1, local=1.3.1
pybind11_vendor : latest=2.4.2, local=2.4.2
rcl : latest=5.3.6, local=5.3.6
ament_cmake_version : latest=1.3.6, local=1.3.6
demo_nodes_py : latest=0.20.3, local=0.20.3
image_tools : latest=0.20.3, local=0.20.3
composition : latest=0.20.3, local=0.20.3
ament_cmake_copyright : latest=0.12.9, local=0.12.9
depthimage_to_laserscan : latest=2.5.1, local=2.5.1
launch : latest=1.0.4, local=1.0.4
action_tutorials_interfaces : latest=0.20.3, local=0.20.3
sensor_msgs : latest=4.2.3, local=4.2.3
rqt_image_view : latest=1.2.0, local=1.2.0
ament_cmake_gen_version_h : latest=1.3.6, local=1.3.6
tf2_eigen_kdl : latest=0.25.5, local=0.25.5
ament_copyright : latest=0.12.9, local=0.12.9
sqlite3_vendor : latest=0.15.8, local=0.15.8
rclcpp : latest=16.0.7, local=16.0.7
rosidl_typesupport_introspection_cpp : latest=3.1.5, local=3.1.5
ament_cmake_core : latest=1.3.6, local=1.3.6
tf2_sensor_msgs : latest=0.25.5, local=0.25.5
ament_cmake_libraries : latest=1.3.6, local=1.3.6
rmw_implementation : latest=2.8.2, local=2.8.2
rqt_reconfigure : latest=1.1.2, local=1.1.2
ros2launch : latest=0.19.6, local=0.19.6
ament_cppcheck : latest=0.12.9, local=0.12.9
ros2component : latest=0.18.7, local=0.18.7
ament_cmake_cppcheck : latest=0.12.9, local=0.12.9
rosidl_typesupport_interface : latest=3.1.5, local=3.1.5
action_tutorials_py : latest=0.20.3, local=0.20.3
tinyxml_vendor : latest=0.8.3, local=0.8.3
uncrustify_vendor : latest=2.0.2, local=2.0.2
eigen3_cmake_module : latest=0.1.1, local=0.1.1
rosbag2_storage_default_plugins : latest=0.15.8, local=0.15.8
class_loader : latest=2.2.0, local=2.2.0
actionlib_msgs : latest=4.2.3, local=4.2.3
rviz2 : latest=11.2.9, local=11.2.9
urdf_parser_plugin : latest=2.6.0, local=2.6.0
ros2interface : latest=0.18.7, local=0.18.7
ament_package : latest=0.14.0, local=0.14.0
launch_testing_ros : latest=0.19.6, local=0.19.6
ament_cmake_test : latest=1.3.6, local=1.3.6
examples_rclpy_minimal_action_server : latest=0.15.1, local=0.15.1
examples_rclcpp_minimal_composition : latest=0.15.1, local=0.15.1
tf2_geometry_msgs : latest=0.25.5, local=0.25.5
ros_core : latest=0.10.0, local=0.10.0
ros2run : latest=0.18.7, local=0.18.7
ament_pep257 : latest=0.12.9, local=0.12.9
ament_cmake_target_dependencies : latest=1.3.6, local=1.3.6
quality_of_service_demo_py : latest=0.20.3, local=0.20.3
quality_of_service_demo_cpp : latest=0.20.3, local=0.20.3
examples_rclpy_minimal_subscriber : latest=0.15.1, local=0.15.1
shape_msgs : latest=4.2.3, local=4.2.3
python_cmake_module : latest=0.10.0, local=0.10.0
demo_nodes_cpp_native : latest=0.20.3, local=0.20.3
ament_cmake : latest=1.3.6, local=1.3.6
qt_gui : latest=2.2.2, local=2.2.2
rqt_publisher : latest=1.5.0, local=1.5.0
console_bridge_vendor : latest=1.4.1, local=1.4.1
examples_rclcpp_minimal_subscriber : latest=0.15.1, local=0.15.1
examples_rclcpp_minimal_timer : latest=0.15.1, local=0.15.1
ament_cmake_flake8 : latest=0.12.9, local=0.12.9
rcl_logging_interface : latest=2.3.1, local=2.3.1
orocos_kdl_vendor : latest=0.2.5, local=0.2.5
rttest : latest=0.13.0, local=0.13.0
rosidl_generator_c : latest=3.1.5, local=3.1.5
examples_rclpy_executors : latest=0.15.1, local=0.15.1
rosidl_parser : latest=3.1.5, local=3.1.5
rqt_graph : latest=1.3.0, local=1.3.0
libstatistics_collector : latest=1.3.1, local=1.3.1
launch_yaml : latest=1.0.4, local=1.0.4
rmw_dds_common : latest=1.6.0, local=1.6.0
rmw_fastrtps_shared_cpp : latest=6.2.5, local=6.2.5
rqt_plot : latest=1.1.2, local=1.1.2
ament_cmake_python : latest=1.3.6, local=1.3.6
rqt_bag_plugins : latest=1.1.4, local=1.1.4
lifecycle_msgs : latest=1.2.1, local=1.2.1
rosidl_adapter : latest=3.1.5, local=3.1.5
rqt_gui_cpp : latest=1.1.5, local=1.1.5
ament_cmake_export_targets : latest=1.3.6, local=1.3.6
dummy_robot_bringup : latest=0.20.3, local=0.20.3
sdl2_vendor : latest=3.3.0, local=3.3.0
rosbag2 : latest=0.15.8, local=0.15.8
action_tutorials_cpp : latest=0.20.3, local=0.20.3
resource_retriever : latest=3.1.1, local=3.1.1
rosidl_default_runtime : latest=1.2.0, local=1.2.0
ros2multicast : latest=0.18.7, local=0.18.7
rqt_bag : latest=1.1.4, local=1.1.4
ament_cmake_cpplint : latest=0.12.9, local=0.12.9
robot_state_publisher : latest=3.0.2, local=3.0.2
examples_rclcpp_minimal_action_server : latest=0.15.1, local=0.15.1
rosbag2_storage : latest=0.15.8, local=0.15.8
ros2topic : latest=0.18.7, local=0.18.7
map_msgs : latest=2.1.0, local=2.1.0
rosidl_default_generators : latest=1.2.0, local=1.2.0
ament_cmake_xmllint : latest=0.12.9, local=0.12.9
rqt_gui_py : latest=1.1.5, local=1.1.5
ament_cmake_export_definitions : latest=1.3.6, local=1.3.6
rosidl_typesupport_fastrtps_cpp : latest=2.2.2, local=2.2.2
dummy_map_server : latest=0.20.3, local=0.20.3
rviz_common : latest=11.2.9, local=11.2.9
rosidl_typesupport_fastrtps_c : latest=2.2.2, local=2.2.2
desktop : latest=0.10.0, local=0.10.0
rmw_implementation_cmake : latest=6.1.1, local=6.1.1
ament_lint_cmake : latest=0.12.9, local=0.12.9
rqt_py_console : latest=1.0.2, local=1.0.2
examples_rclcpp_minimal_client : latest=0.15.1, local=0.15.1
tf2_tools : latest=0.25.5, local=0.25.5
example_interfaces : latest=0.9.3, local=0.9.3
qt_gui_py_common : latest=2.2.2, local=2.2.2
ros_workspace : latest=1.0.2, local=1.0.2
rosidl_typesupport_introspection_c : latest=3.1.5, local=3.1.5
builtin_interfaces : latest=1.2.1, local=1.2.1
tf2 : latest=0.25.5, local=0.25.5
lifecycle : latest=0.20.3, local=0.20.3
rosgraph_msgs : latest=1.2.1, local=1.2.1
teleop_twist_keyboard : latest=2.3.2, local=2.3.2
common_interfaces : latest=4.2.3, local=4.2.3
examples_rclpy_minimal_publisher : latest=0.15.1, local=0.15.1

   PLATFORM INFORMATION
system : Linux
platform info : Linux-5.15.0-1043-raspi-aarch64-with-glibc2.35
release : 5.15.0-1043-raspi
processor : aarch64

   QOS COMPATIBILITY LIST
compatibility status : No publisher/subscriber pairs found

   RMW MIDDLEWARE
middleware name : rmw_fastrtps_cpp

   ROS 2 INFORMATION
distribution name : humble
distribution type : ros2
distribution status : active
release platforms : {'debian': ['bullseye'], 'rhel': ['8'], 'ubuntu': ['jammy']}

   TOPIC LIST
topic : /fmu/in/obstacle_distance
publisher count : 0
subscriber count : 1
topic : /fmu/in/offboard_control_mode
publisher count : 0
subscriber count : 1
topic : /fmu/in/onboard_computer_status
publisher count : 0
subscriber count : 1
topic : /fmu/in/sensor_optical_flow
publisher count : 0
subscriber count : 1
topic : /fmu/in/telemetry_status
publisher count : 0
subscriber count : 1
topic : /fmu/in/trajectory_setpoint
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_attitude_setpoint
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_command
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_mocap_odometry
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_rates_setpoint
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_trajectory_bezier
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_trajectory_waypoint
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_visual_odometry
publisher count : 0
subscriber count : 1
topic : /fmu/out/failsafe_flags
publisher count : 1
subscriber count : 0
topic : /fmu/out/position_setpoint_triplet
publisher count : 1
subscriber count : 0
topic : /fmu/out/sensor_combined
publisher count : 1
subscriber count : 0
topic : /fmu/out/timesync_status
publisher count : 1
subscriber count : 0
topic : /fmu/out/vehicle_attitude
publisher count : 1
subscriber count : 0
topic : /fmu/out/vehicle_control_mode
publisher count : 1
subscriber count : 0
topic : /fmu/out/vehicle_local_position
publisher count : 1
subscriber count : 0
topic : /fmu/out/vehicle_odometry
publisher count : 1
subscriber count : 0
topic : /fmu/out/vehicle_status
publisher count : 1
subscriber count : 0

```

Any help would be really Appreciated !  
Thank you

---

<div class="post-metadata">

**Author:** ![Benja](https://discuss.px4.io/user_avatar/discuss.px4.io/benja/32/11872_2.png) [@Benja](https://discuss.px4.io/u/Benja)\
**Post date:** [December 9, 2023, 7:11am UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/2 "2023-12-09T07:11:06Z")

</div>

Do you have the same error message if you don’t start the agent?

---

<div class="post-metadata">

**Author:** ![Gradle](https://discuss.px4.io/user_avatar/discuss.px4.io/gradle/32/14171_2.png) [@Gradle](https://discuss.px4.io/u/Gradle)\
**Post date:** [December 9, 2023, 7:58am UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/3 "2023-12-09T07:58:32Z")

</div>

Hi Benja, Without starting the Agent when I run -

> ros2 topic list

OUTPUT

```auto
/parameter_events
/rosout

```

> ros2 topic echo /fmu/out/vehicle\_status

OUTPUT

```auto
WARNING: topic [/fmu/out/vehicle_status] does not appear to be published yet
Could not determine the type for the passed topic

```

NOTE: I have RPI 4B 8gb (Original)

NO Errors as such in terms of output from what I understand!

---

<div class="post-metadata">

**Author:** ![Gradle](https://discuss.px4.io/user_avatar/discuss.px4.io/gradle/32/14171_2.png) [@Gradle](https://discuss.px4.io/u/Gradle)\
**Post date:** [December 9, 2023, 10:13am UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/4 "2023-12-09T10:13:35Z")

</div>

After the agent runs  
ROS is not able to get data from the agent.  
ROS\_DOMAIN\_ID=0 same as uxrce\_dds\_dom\_id

```auto
kds-ros@kdsros-desktop:~/ws_sensor_combined$ source /opt/ros/humble/setup.bash
kds-ros@kdsros-desktop:~/ws_sensor_combined$ source install/local_setup.bash
kds-ros@kdsros-desktop:~/ws_sensor_combined$ . /install/local_setup.bash
bash: /install/local_setup.bash: No such file or directory
kds-ros@kdsros-desktop:~/ws_sensor_combined$ . install/local_setup.bash
kds-ros@kdsros-desktop:~/ws_sensor_combined$ ros2 topic list
/fmu/in/obstacle_distance
/fmu/in/offboard_control_mode
/fmu/in/onboard_computer_status
/fmu/in/sensor_optical_flow
/fmu/in/telemetry_status
/fmu/in/trajectory_setpoint
/fmu/in/vehicle_attitude_setpoint
/fmu/in/vehicle_command
/fmu/in/vehicle_mocap_odometry
/fmu/in/vehicle_rates_setpoint
/fmu/in/vehicle_trajectory_bezier
/fmu/in/vehicle_trajectory_waypoint
/fmu/in/vehicle_visual_odometry
/fmu/out/failsafe_flags
/fmu/out/position_setpoint_triplet
/fmu/out/timesync_status
/fmu/out/vehicle_control_mode
/fmu/out/vehicle_status
/parameter_events
/rosout
kds-ros@kdsros-desktop:~/ws_sensor_combined$ ros2 topic echo /fmu/out/vehicle_status

^Z
[1]+ Stopped ros2 topic echo /fmu/out/vehicle_status
kds-ros@kdsros-desktop:~/ws_sensor_combined$ ros2 topic echo /fmu/out/vehicle_status
 
^Z
[2]+ Stopped ros2 topic echo /fmu/out/vehicle_status
kds-ros@kdsros-desktop:~/ws_sensor_combined$ 
kds-ros@kdsros-desktop:~/ws_sensor_combined$ ros2 topic echo /fmu/out/vehicle_status
2023-12-09 15:35:43.099 [RTPS_TRANSPORT_SHM Error] Failed init_port fastrtps_port7413: open_and_lock_file failed -> Function open_port_internal
^Z
[3]+ Stopped ros2 topic echo /fmu/out/vehicle_status
kds-ros@kdsros-desktop:~/ws_sensor_combined$ ros2 launch px4_ros_com sensor_combined_listener.launch.py 
[INFO] [launch]: All log files can be found below /home/kds-ros/.ros/log/2023-12-09-15-36-02-564547-kdsros-desktop-15718
[INFO] [launch]: Default logging verbosity is set to INFO
[INFO] [sensor_combined_listener-1]: process started with pid [15719]
[sensor_combined_listener-1] Starting sensor_combined listener node...
[sensor_combined_listener-1] 2023-12-09 15:36:03.047 [RTPS_TRANSPORT_SHM Error] Failed init_port fastrtps_port7413: open_and_lock_file failed -> Function open_port_internal
[sensor_combined_listener-1] 2023-12-09 15:36:03.048 [RTPS_TRANSPORT_SHM Error] Failed init_port fastrtps_port7415: open_and_lock_file failed -> Function open_port_internal
^Z
[4]+ Stopped ros2 launch px4_ros_com sensor_combined_listener.launch.py
kds-ros@kdsros-desktop:~/ws_sensor_combined$ 

```

```auto
   PLATFORM INFORMATION
system : Linux
platform info : Linux-5.15.0-1043-raspi-aarch64-with-glibc2.35
release : 5.15.0-1043-raspi
processor : aarch64

   QOS COMPATIBILITY LIST
compatibility status : No publisher/subscriber pairs found

   RMW MIDDLEWARE
middleware name : rmw_fastrtps_cpp

   ROS 2 INFORMATION
distribution name : humble
distribution type : ros2
distribution status : active
release platforms : {'debian': ['bullseye'], 'rhel': ['8'], 'ubuntu': ['jammy']}

   TOPIC LIST
topic : /fmu/in/obstacle_distance
publisher count : 0
subscriber count : 1
topic : /fmu/in/offboard_control_mode
publisher count : 0
subscriber count : 1
topic : /fmu/in/onboard_computer_status
publisher count : 0
subscriber count : 1
topic : /fmu/in/sensor_optical_flow
publisher count : 0
subscriber count : 1
topic : /fmu/in/telemetry_status
publisher count : 0
subscriber count : 1
topic : /fmu/in/trajectory_setpoint
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_attitude_setpoint
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_command
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_mocap_odometry
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_rates_setpoint
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_trajectory_bezier
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_trajectory_waypoint
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_visual_odometry
publisher count : 0
subscriber count : 1
topic : /fmu/out/failsafe_flags
publisher count : 1
subscriber count : 0
topic : /fmu/out/position_setpoint_triplet
publisher count : 1
subscriber count : 0
topic : /fmu/out/timesync_status
publisher count : 1
subscriber count : 0
topic : /fmu/out/vehicle_control_mode
publisher count : 1
subscriber count : 0
topic : /fmu/out/vehicle_status
publisher count : 1
subscriber count : 0
kds-ros@kdsros-desktop:~/ws_sensor_combined$ 

```

After the agent runs  
ROS is not able to get data from the agent.  
ROS\_DOMAIN\_ID=0 same as uxrce\_dds\_dom\_id

```auto
kds-ros@kdsros-desktop:~/ws_sensor_combined$ source /opt/ros/humble/setup.bash
kds-ros@kdsros-desktop:~/ws_sensor_combined$ source install/local_setup.bash
kds-ros@kdsros-desktop:~/ws_sensor_combined$ . /install/local_setup.bash
bash: /install/local_setup.bash: No such file or directory
kds-ros@kdsros-desktop:~/ws_sensor_combined$ . install/local_setup.bash
kds-ros@kdsros-desktop:~/ws_sensor_combined$ ros2 topic list
/fmu/in/obstacle_distance
/fmu/in/offboard_control_mode
/fmu/in/onboard_computer_status
/fmu/in/sensor_optical_flow
/fmu/in/telemetry_status
/fmu/in/trajectory_setpoint
/fmu/in/vehicle_attitude_setpoint
/fmu/in/vehicle_command
/fmu/in/vehicle_mocap_odometry
/fmu/in/vehicle_rates_setpoint
/fmu/in/vehicle_trajectory_bezier
/fmu/in/vehicle_trajectory_waypoint
/fmu/in/vehicle_visual_odometry
/fmu/out/failsafe_flags
/fmu/out/position_setpoint_triplet
/fmu/out/timesync_status
/fmu/out/vehicle_control_mode
/fmu/out/vehicle_status
/parameter_events
/rosout
kds-ros@kdsros-desktop:~/ws_sensor_combined$ ros2 topic echo /fmu/out/vehicle_status

^Z
[1]+ Stopped ros2 topic echo /fmu/out/vehicle_status
kds-ros@kdsros-desktop:~/ws_sensor_combined$ ros2 topic echo /fmu/out/vehicle_status
 
^Z
[2]+ Stopped ros2 topic echo /fmu/out/vehicle_status
kds-ros@kdsros-desktop:~/ws_sensor_combined$ 
kds-ros@kdsros-desktop:~/ws_sensor_combined$ ros2 topic echo /fmu/out/vehicle_status
2023-12-09 15:35:43.099 [RTPS_TRANSPORT_SHM Error] Failed init_port fastrtps_port7413: open_and_lock_file failed -> Function open_port_internal
^Z
[3]+ Stopped ros2 topic echo /fmu/out/vehicle_status
kds-ros@kdsros-desktop:~/ws_sensor_combined$ ros2 launch px4_ros_com sensor_combined_listener.launch.py 
[INFO] [launch]: All log files can be found below /home/kds-ros/.ros/log/2023-12-09-15-36-02-564547-kdsros-desktop-15718
[INFO] [launch]: Default logging verbosity is set to INFO
[INFO] [sensor_combined_listener-1]: process started with pid [15719]
[sensor_combined_listener-1] Starting sensor_combined listener node...
[sensor_combined_listener-1] 2023-12-09 15:36:03.047 [RTPS_TRANSPORT_SHM Error] Failed init_port fastrtps_port7413: open_and_lock_file failed -> Function open_port_internal
[sensor_combined_listener-1] 2023-12-09 15:36:03.048 [RTPS_TRANSPORT_SHM Error] Failed init_port fastrtps_port7415: open_and_lock_file failed -> Function open_port_internal
^Z
[4]+ Stopped ros2 launch px4_ros_com sensor_combined_listener.launch.py
kds-ros@kdsros-desktop:~/ws_sensor_combined$ 

```

```auto
   PLATFORM INFORMATION
system : Linux
platform info : Linux-5.15.0-1043-raspi-aarch64-with-glibc2.35
release : 5.15.0-1043-raspi
processor : aarch64

   QOS COMPATIBILITY LIST
compatibility status : No publisher/subscriber pairs found

   RMW MIDDLEWARE
middleware name : rmw_fastrtps_cpp

   ROS 2 INFORMATION
distribution name : humble
distribution type : ros2
distribution status : active
release platforms : {'debian': ['bullseye'], 'rhel': ['8'], 'ubuntu': ['jammy']}

   TOPIC LIST
topic : /fmu/in/obstacle_distance
publisher count : 0
subscriber count : 1
topic : /fmu/in/offboard_control_mode
publisher count : 0
subscriber count : 1
topic : /fmu/in/onboard_computer_status
publisher count : 0
subscriber count : 1
topic : /fmu/in/sensor_optical_flow
publisher count : 0
subscriber count : 1
topic : /fmu/in/telemetry_status
publisher count : 0
subscriber count : 1
topic : /fmu/in/trajectory_setpoint
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_attitude_setpoint
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_command
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_mocap_odometry
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_rates_setpoint
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_trajectory_bezier
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_trajectory_waypoint
publisher count : 0
subscriber count : 1
topic : /fmu/in/vehicle_visual_odometry
publisher count : 0
subscriber count : 1
topic : /fmu/out/failsafe_flags
publisher count : 1
subscriber count : 0
topic : /fmu/out/position_setpoint_triplet
publisher count : 1
subscriber count : 0
topic : /fmu/out/timesync_status
publisher count : 1
subscriber count : 0
topic : /fmu/out/vehicle_control_mode
publisher count : 1
subscriber count : 0
topic : /fmu/out/vehicle_status
publisher count : 1
subscriber count : 0
kds-ros@kdsros-desktop:~/ws_sensor_combined$ 

```

---

<div class="post-metadata">

**Author:** ![Gradle](https://discuss.px4.io/user_avatar/discuss.px4.io/gradle/32/14171_2.png) [@Gradle](https://discuss.px4.io/u/Gradle)\
**Post date:** [December 11, 2023, 12:42pm UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/5 "2023-12-11T12:42:21Z")

</div>

Hi @Benja, I was trying to connect using **PX4 HITL on Cube** and I think that is why the ros2\_ws was not able to subscribe to the topics. When I updated it to regular FW, I am able to subscribe to topics.  
Though still not able to echo topic, gives an output -  
The message type 'px4\_msgs/msg/VehicleStatus is invalid.

Just a suggestion - If UXRCE\_DDS doesn’t work with HITL(if its correct), updating it on documentation would help others too.

---

<div class="post-metadata">

**Author:** ![Olivier\_Olivier](https://discuss.px4.io/user_avatar/discuss.px4.io/olivier_olivier/32/12242_2.png) [@Olivier\_Olivier](https://discuss.px4.io/u/Olivier_Olivier)\
**Post date:** [December 12, 2023, 12:51pm UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/6 "2023-12-12T12:51:59Z")

</div>

I have a similar problem with a fresh install…

I can’t echo some topics, and i can echo some also ?!!

with another computer it’s working…

---

<div class="post-metadata">

**Author:** ![Gradle](https://discuss.px4.io/user_avatar/discuss.px4.io/gradle/32/14171_2.png) [@Gradle](https://discuss.px4.io/u/Gradle)\
**Post date:** [December 12, 2023, 1:05pm UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/7 "2023-12-12T13:05:19Z")

</div>

Do you have a companion computer with the pixhawk ?

---

<div class="post-metadata">

**Author:** ![Olivier\_Olivier](https://discuss.px4.io/user_avatar/discuss.px4.io/olivier_olivier/32/12242_2.png) [@Olivier\_Olivier](https://discuss.px4.io/u/Olivier_Olivier)\
**Post date:** [December 12, 2023, 1:21pm UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/8 "2023-12-12T13:21:13Z")

</div>

yes a raspbery pi 4 with ubuntu 22.04 server…  
It was working with my old installation of ubuntu 22.04 desktop on another raspbery

---

<div class="post-metadata">

**Author:** ![Gradle](https://discuss.px4.io/user_avatar/discuss.px4.io/gradle/32/14171_2.png) [@Gradle](https://discuss.px4.io/u/Gradle)\
**Post date:** [December 13, 2023, 5:35am UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/9 "2023-12-13T05:35:57Z")

</div>

Hey Oliver, You can try this if you are not able to echo (worked for me).  
In your ROS workspace

```auto
source /opt/ros/humble/setup.bash
source install/local_setup.bash
export ROS_DOMAIN_ID=0
export PYTHONOPTIMIZE=1
ros2 topic list
ros2 topic echo /fmu/out/vehicle_status

```

This should start to give you output.

---

<div class="post-metadata">

**Author:** ![Olivier\_Olivier](https://discuss.px4.io/user_avatar/discuss.px4.io/olivier_olivier/32/12242_2.png) [@Olivier\_Olivier](https://discuss.px4.io/u/Olivier_Olivier)\
**Post date:** [December 13, 2023, 7:46am UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/10 "2023-12-13T07:46:18Z")

</div>

all is sourced ans i have the correct ros domain , i can list the topics and echo some, but i don’t know why some topics don’t want to be open , i can echo odometry for exmple and i can’t echo vehicle local position ?!!!

---

<div class="post-metadata">

**Author:** ![Theotime\_Balaguer](https://discuss.px4.io/letter_avatar_proxy/v4/letter/t/cab0a1/32.png) [@Theotime\_Balaguer](https://discuss.px4.io/u/Theotime_Balaguer)\
**Post date:** [December 15, 2023, 11:40am UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/11 "2023-12-15T11:40:44Z")

</div>

I had similar problems and I am pretty sure this comes from incompatibility between the `px4 firmware` and `px4_msgs`.

I posted this to the discord, I’ll share it again here :

> Hi there, can someone please confirm that `PX4 Autopilot 1.14` with MicroXRCE-DDS Bridge should work with `px4_msgs 1.14` ?
> 
> I have a strange behavior where I cannot echo some topics, but other topics work (for instance, `vehicle_odometry` works, but `vehicle_status` doesn’t).
> 
> I just tested with a fresh main build and all the messages go through. So this is my conclusion :
> 
> - PX4 `release/1.14` (634ad3893e) with px4\_msgs `release/1.14` (33dc666) doesn’t work
> - PX4 `main` (1c25d65a1e) with px4\_msgs `release/1.14` (33dc666) works

So I made it work with a rollback to an older version of `px4_msgs`, but I didn’t manage to find what broke the compatibility…

---

<div class="post-metadata">

**Author:** ![Benja](https://discuss.px4.io/user_avatar/discuss.px4.io/benja/32/11872_2.png) [@Benja](https://discuss.px4.io/u/Benja)\
**Post date:** [December 17, 2023, 7:49pm UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/12 "2023-12-17T19:49:16Z")

</div>

px4\_msgs release/1.14 has no 33dc666 commit

if you check [GitHub - PX4/px4\_msgs at release/1.14](https://github.com/PX4/px4_msgs/tree/release/1.14) and [GitHub - PX4/PX4-Autopilot at release/1.14](https://github.com/PX4/PX4-Autopilot/tree/release/1.14) you will see that the messages definition are perfectly in sync

---

<div class="post-metadata">

**Author:** ![Olivier\_Olivier](https://discuss.px4.io/user_avatar/discuss.px4.io/olivier_olivier/32/12242_2.png) [@Olivier\_Olivier](https://discuss.px4.io/u/Olivier_Olivier)\
**Post date:** [December 19, 2023, 2:31pm UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/13 "2023-12-19T14:31:40Z")

</div>

Me too, lot off problems depending off the version off px4 and px4\_msgs,

Also offboard don’t work for me now, it was working perfgecly before, i put px4 in offboard and i publish on /fmu/in/vehicle\_torque\_setpoint… Now is broken and don’t work ?  
Also topic names have changed , before i subcribe to /fmu/out/sensor\_gps ,now it’s /fmu/out/vehicle\_gps\_position , and the names off messages changed also !! it was lat, lon, alt, and now it’s latitude\_deg longitude\_deg and altitude\_msl\_m

---

<div class="post-metadata">

**Author:** ![Benja](https://discuss.px4.io/user_avatar/discuss.px4.io/benja/32/11872_2.png) [@Benja](https://discuss.px4.io/u/Benja)\
**Post date:** [December 27, 2023, 12:28pm UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/14 "2023-12-27T12:28:27Z")

</div>

> [@Olivier\_Olivier](#):
>
> Also topic names have changed , before i subcribe to /fmu/out/sensor\_gps ,now it’s /fmu/out/vehicle\_gps\_position , and the names off messages changed also !! it was lat, lon, alt, and now it’s latitude\_deg longitude\_deg and altitude\_msl\_m

You are comparing the stable version of PX4 (and px4\_msgs) with the `main` branch, where all the development happens, you have to expect the message definition of the `main` branch to change

---

<div class="post-metadata">

**Author:** ![Theotime\_Balaguer](https://discuss.px4.io/letter_avatar_proxy/v4/letter/t/cab0a1/32.png) [@Theotime\_Balaguer](https://discuss.px4.io/u/Theotime_Balaguer)\
**Post date:** [January 4, 2024, 10:01am UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/15 "2024-01-04T10:01:10Z")

</div>

Sorry about that, my mistake.

I also think I have messed up with the git commands when I did this test some time ago… So please ignore my previous message, the issue probably originate from a version mismatch between px4 and px4\_msgs.

However, I am surprised that ROS2 didn’t come up with error messages when the message definitions are off. The subscriber seems to work, but never receives messages.

---

<div class="post-metadata">

**Author:** ![Benja](https://discuss.px4.io/user_avatar/discuss.px4.io/benja/32/11872_2.png) [@Benja](https://discuss.px4.io/u/Benja)\
**Post date:** [January 14, 2024, 10:27am UTC](https://discuss.px4.io/t/ros2-uxrce-agent-cant-subscribe-to-published-topics/35734/16 "2024-01-14T10:27:18Z")

</div>

Good to hear that!

The [PX4 ROS2 interface library](https://docs.px4.io/main/en/ros2/px4_ros2_interface_lib.html) library provides a way to check if the messages are synchronized at runtime