# Problems with some px4 ros topics

**URL:** <https://discuss.px4.io/t/problems-with-some-px4-ros-topics/35854>\
**Category:** ROS 1 / ROS 2\
**Created:** [December 12, 2023, 12:48pm UTC](https://discuss.px4.io/t/problems-with-some-px4-ros-topics/35854 "2023-12-12T12:48:12Z")\
**Posts on this page:** 7\
**Page:** 1

<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, 12:48pm UTC](https://discuss.px4.io/t/problems-with-some-px4-ros-topics/35854/1 "2023-12-12T12:48:12Z")

</div>

Hello, i have some topics from px4 i can’t echo ??!  
They are present on tiopic list , but some can’t be read.  
i have done a fresh install of ubuntu server 22.04 on a raspbery.  
Installed humble from deb , microxrce agent via snap, and px4\_msgs from git  
All is sourced, I can start the agent and see the topics, but i can’t echo /fmu/out/vehicle\_local\_position or vehicle\_air\_data… and i can echo some topics like odometry…

here is the output from my controler node :

```auto
 python3 CTL.py 

>>> [rcutils|error_handling.c:108] rcutils_set_error_state()
This error state is being overwritten:

  'Fast CDR exception deserializing message of type px4_msgs::msg::dds_::VehicleLocalPosition_., at ./src/type_support_common.cpp:118'

with this new error message:

  'Fast CDR exception deserializing message of type px4_msgs::msg::dds_::VehicleAirData_., at ./src/type_support_common.cpp:118'

rcutils_reset_error() should be called after error handling to avoid this.
<<<

>>> [rcutils|error_handling.c:108] rcutils_set_error_state()
This error state is being overwritten:

  'Fast CDR exception deserializing message of type px4_msgs::msg::dds_::VehicleAirData_., at ./src/type_support_common.cpp:118'

with this new error message:

  'Fast CDR exception deserializing message of type px4_msgs::msg::dds_::VehicleLocalPosition_., at ./src/type_support_common.cpp:118'

rcutils_reset_error() should be called after error handling to avoid this.
<<<

>>> [rcutils|error_handling.c:108] rcutils_set_error_state()
This error state is being overwritten:

  'Fast CDR exception deserializing message of type px4_msgs::msg::dds_::VehicleLocalPosition_., at ./src/type_support_common.cpp:118'

with this new error message:

  'Fast CDR exception deserializing message of type px4_msgs::msg::dds_::VehicleAirData_., at ./src/type_support_common.cpp:118'

rcutils_reset_error() should be called after error handling to avoid this.
<<<

>>> [rcutils|error_handling.c:108] rcutils_set_error_state()
This error state is being overwritten:

  'Fast CDR exception deserializing message of type px4_msgs::msg::dds_::VehicleAirData_., at ./src/type_support_common.cpp:118'

with this new error message:

  'Fast CDR exception deserializing message of type px4_msgs::msg::dds_::SensorGps_., at ./src/type_support_common.cpp:118'

rcutils_reset_error() should be called after error handling to avoid this.
<<<

>>> [rcutils|error_handling.c:108] rcutils_set_error_state()
This error state is being overwritten:

  'Fast CDR exception deserializing message of type px4_msgs::msg::dds_::SensorGps_., at ./src/type_support_common.cpp:118'

with this new error message:

  'Fast CDR exception deserializing message of type px4_msgs::msg::dds_::VehicleLocalPosition_., at ./src/type_support_common.cpp:118'

rcutils_reset_error() should be called after error handling to avoid this.
<<<

>>> [rcutils|error_handling.c:108] rcutils_set_error_state()
This error state is being overwritten:

```

I can echo this topics from my others computers, and CTL.py work.  
I think the problem come from px4\_msgs on the fresh install ?

Why some topics works like /fmu/out/vehicle\_odometry or /fmu/out/vehicle\_attitude ?

Thanks for any help

---

<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, 7:52pm UTC](https://discuss.px4.io/t/problems-with-some-px4-ros-topics/35854/2 "2023-12-17T19:52:56Z")

</div>

please install the agent from source or make sure you are using the `latest/edge` snap version

---

<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, 2:18pm UTC](https://discuss.px4.io/t/problems-with-some-px4-ros-topics/35854/3 "2023-12-19T14:18:57Z")

</div>

Hello, the problem comes from px4\_msg

the main branche off px4\_msgs don’t work with the stable version off px4 , i have to install de dev branch of px4 to make it work…

I’m totally confused , all was working perfectly before , now i have some stranges thinks… :  
For exemple my ros2 node publish command on the topic /fmu/in/vehicle\_torque\_setpoint , I change px4 mode to offboard with my rc tranmiter , and ros was able to control my vehicle , now it’s impossible ??! why ? i publish my command on /fmu/in/vehiclme\_torque\_setpoint , and i’m in offboard mode but nothing moove… How to do to make it work like before ? Thanks for your help

---

<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, 12:26pm UTC](https://discuss.px4.io/t/problems-with-some-px4-ros-topics/35854/4 "2023-12-27T12:26:25Z")

</div>

@Olivier_Olivier

> the main branche off px4\_msgs don’t work with the stable version off px4 , i have to install de dev branch of px4 to make it work…

px4\_msgs `main` branch has to be used with PX4 `main` branch and nothing else.

For the PX4 stable releases you have to use the corresponding px4\_msgs branches as expleined in the README

> **[GitHub - PX4/px4\_msgs: ROS/ROS2 messages that match the uORB messages...](https://github.com/PX4/px4_msgs?tab=readme-ov-file#supported-versions-and-compatibility)**
>
> ROS/ROS2 messages that match the uORB messages counterparts on the PX4 Firmware - GitHub - PX4/px4\_msgs: ROS/ROS2 messages that match the uORB messages counterparts on the PX4 Firmware

> [@Olivier\_Olivier](#):
>
> For exemple my ros2 node publish command on the topic /fmu/in/vehicle\_torque\_setpoint , I change px4 mode to offboard with my rc tranmiter , and ros was able to control my vehicle , now it’s impossible ??!

If you are using PX4 `main` branch, then check this [[offboard control] allow for direct actuator control by beniaminopozzan · Pull Request #22222 · PX4/PX4-Autopilot · GitHub](https://github.com/PX4/PX4-Autopilot/pull/22222) and the updated documentation in the docs

---

<div class="post-metadata">

**Author:** ![insidefpv\_rnd](https://discuss.px4.io/user_avatar/discuss.px4.io/insidefpv_rnd/32/15775_2.png) [@insidefpv\_rnd](https://discuss.px4.io/u/insidefpv_rnd)\
**Post date:** [February 22, 2024, 6:36am UTC](https://discuss.px4.io/t/problems-with-some-px4-ros-topics/35854/5 "2024-02-22T06:36:00Z")

</div>

Hi @Olivier_Olivier did you solve this? If yes please let me know how, cause I am also getting the same error. I am using:  
-Jetson orin nano dev kit  
-Jetpack- 6.0  
-ubuntu- 22.04  
-ROS2 Humble and latest version of MicroXRCE-DDS-Agent and client i.e. v2.4.2  
This is the error I am getting:

```auto
 >>> [rcutils|error_handling.c:108] rcutils_set_error_state()
This error state is being overwritten:

  'Fast CDR exception deserializing message of type px4_msgs::msg::dds_::VehicleLocalPosition_., at ./src/type_support_common.cpp:118'

with this new error message:

  'Fast CDR exception deserializing message of type px4_msgs::msg::dds_::VehicleStatus_., at ./src/type_support_common.cpp:118'

Blockquote

rcutils_reset_error() should be called after error handling to avoid this.
<<< 

```

It’s working fine on my laptop which has same things installed as mentioned above but the older version of agent and client i.e v2.4.1  
Also please help me if you know how to downgrade the version from v2.4.2 to v2.4.1

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<div class="post-metadata">

**Author:** ![Nathan\_Cannon](https://discuss.px4.io/user_avatar/discuss.px4.io/nathan_cannon/32/15768_2.png) [@Nathan\_Cannon](https://discuss.px4.io/u/Nathan_Cannon)\
**Post date:** [March 11, 2024, 9:27pm UTC](https://discuss.px4.io/t/problems-with-some-px4-ros-topics/35854/6 "2024-03-11T21:27:17Z")

</div>

Did you ever figure this one out?

---

<div class="post-metadata">

**Author:** ![insidefpv\_rnd](https://discuss.px4.io/user_avatar/discuss.px4.io/insidefpv_rnd/32/15775_2.png) [@insidefpv\_rnd](https://discuss.px4.io/u/insidefpv_rnd)\
**Post date:** [March 26, 2024, 11:09am UTC](https://discuss.px4.io/t/problems-with-some-px4-ros-topics/35854/7 "2024-03-26T11:09:01Z")

</div>

@Nathan_Cannon It worked with the older px4\_msgs package which was working in my laptop. [here](https://drive.google.com/drive/folders/1AcOH9ObSTAUnbKL1eEp3lCurhPpPvVze?usp=sharing) is the link. you can try with this px4\_msgs, it just worked for me.