PX4 SITL: no connection to QgroundControl?

PX4 Autopilot
1

Ubuntu 24.04.2 LTS, PX4 v1.15.4

Today I downloaded the latest stable version of PX4, and several QgroundControl images.
PX4 built without errors, but make px4_sitl gz_x500 fails on takeoff messages listed below.

I attempted to diagnose a connection failure: Please correct me , but I assume the following means that QgroundControl is trying to communicate on
0.0.0.0:14550, but neither PX4 nor gz sim are listening to that.

What is supposed to be happening ? What should I do to fix this ?

Not the same problem as Profile - lux_nychta - Discussion Forum for PX4, Pixhawk, QGroundControl, MAVSDK, MAVLink
================ PX4 =============================
make px4_sitl gz_x500
……

INFO [commander] Ready for takeoff!
ERROR [sensors] Accel #0 fail: TIMEOUT!
ERROR [sensors] Accel #0 fail: TIMEOUT!
WARN [health_and_arming_checks] Preflight Fail: High Accelerometer Bias
ERROR [sensors] Accel #0 fail: TIMEOUT!
ERROR [sensors] Accel #0 fail: TIMEOUT!
ERROR [sensors] Accel #0 fail: TIMEOUT!
ERROR [sensors] Accel #0 fail: TIMEOUT!
ERROR [sensors] Accel #0 fail: TIMEOUT!
INFO [commander] Connection to ground station lost
WARN [health_and_arming_checks] Preflight Fail: High Accelerometer Bias
WARN [health_and_arming_checks] Preflight Fail: No connection to the ground control station
INFO [commander] GCS connection regained
WARN [health_and_arming_checks] Preflight Fail: High Accelerometer Bias
ERROR [sensors] Accel #0 fail: TIMEOUT!
WARN [health_and_arming_checks] Preflight Fail: vertical velocity unstable
…. continues like this ….

================ Connections =============================
sudo netstat -tulnp | grep 14550
udp 0 0 0.0.0.0:14550 0.0.0.0:* 40366/QGroundContro

$ sudo netstat -tulnp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 192.168.20.18:33155 0.0.0.0:* LISTEN 44405/gz sim -g
tcp 0 0 192.168.20.18:33707 0.0.0.0:* LISTEN 44404/gz sim --verb
tcp 0 0 127.0.0.54:53 0.0.0.0:* LISTEN 1047/systemd-resolv
tcp 0 0 192.168.20.18:36853 0.0.0.0:* LISTEN 44244/px4
tcp 0 0 192.168.20.18:39561 0.0.0.0:* LISTEN 44244/px4
tcp 0 0 192.168.20.18:39553 0.0.0.0:* LISTEN 44405/gz sim -g
tcp 0 0 127.0.0.53:53 0.0.0.0:* LISTEN 1047/systemd-resolv
tcp 0 0 192.168.20.18:44487 0.0.0.0:* LISTEN 44244/px4
tcp 0 0 192.168.20.18:46225 0.0.0.0:* LISTEN 44405/gz sim -g
tcp 0 0 192.168.20.18:46655 0.0.0.0:* LISTEN 44404/gz sim --verb
tcp 0 0 192.168.20.18:45669 0.0.0.0:* LISTEN 44404/gz sim --verb
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN 1761/cupsd
tcp6 0 0 :::80 :::* LISTEN 1832/apache2
tcp6 0 0 ::1:631 :::* LISTEN 1761/cupsd
udp 208768 212992 0.0.0.0:10317 0.0.0.0:* 44244/px4
udp 128128 212992 0.0.0.0:10317 0.0.0.0:* 44404/gz sim --verb
udp 168576 107136 0.0.0.0:10317 0.0.0.0:* 44405/gz sim -g
udp 0 1792 0.0.0.0:10318 0.0.0.0:* 44244/px4
udp 0 135296 0.0.0.0:10318 0.0.0.0:* 44404/gz sim --verb
udp 0 90240 0.0.0.0:10318 0.0.0.0:* 44405/gz sim -g
udp 0 0 0.0.0.0:13030 0.0.0.0:* 44244/px4
udp 0 0 0.0.0.0:14280 0.0.0.0:* 44244/px4
udp 0 0 0.0.0.0:14550 0.0.0.0:* 40366/QGroundContro
udp 0 0 0.0.0.0:14580 0.0.0.0:* 44244/px4
udp 0 0 127.0.0.54:53 0.0.0.0:* 1047/systemd-resolv
udp 0 0 127.0.0.53:53 0.0.0.0:* 1047/systemd-resolv
udp 0 0 0.0.0.0:18570 0.0.0.0:* 44244/px4
udp 0 0 0.0.0.0:5353 0.0.0.0:* 1242/avahi-daemon:
udp 0 0 0.0.0.0:54842 0.0.0.0:* 1242/avahi-daemon:
udp6 0 0 :::41397 :::* 1242/avahi-daemon:
udp6 0 0 fe80::bf84:f439:94b:546 :::* 1350/NetworkManager
udp6 0 0 :::5353 :::* 1242/avahi-daemon:

2

This shouldn’t happen, and doesn’t happen for me. Is this a setup in a virtual machine? Just wondering if the CPU is struggling?

3

Thanks Julian for your reply.
I would not expect the CPU to be struggling. It is an Acer Nitro 5 (low end gaming laptop:
Intel® Core™ i5-10300H × 8, NVIDIA GeForce RTX™ 3060 Laptop GPU ) with 32 GB ram added. Running native Ubuntu 24.04.2 LTS, with nearly daily updates.

I know little about system software, but it seems to me unfortunate that PX4 is so heavily dependent on system details, and that PX4 v1.15.4 resorts to using in ubuntu.sh:

python3 -m pip install --break-system-packages -r ${DIR}/requirements.txt

irrespective of whether or not this is related to my problem.
In my case it is not safe and it doesn’t even give me a working build.

I’m thinking of going back to PX4 v1.15.2 and attempting to use a Python virtual environment as suggested by Error at Installation of PX4 development environment

Is that a reasonable way for me to try? And if so, in Tools/setup/requirements.txt do I need matplotlib>=3.0.*
Can I safely delete that line? Or is there an alternative that would build ok?

Regards,
Don

4

That should be plenty powerful, so that’s not the reason then.

The Python packages shouldn’t be a problem either.

That’s fine. I don’t think that’s required for SITL.

Have you tried with latest main? Does that work better?

5

Thanks Julian,
What is “latest main” ? I will try that if I understand what it is and where to find it - my knowledge of PX4 is very limited.

Since I didn’t know you would reply, I yesterday tried hacking PX4 v1.15.2 to run on Ubuntu 24.04.2 LTS, with what appears to be success - maybe.

  1. I roughly hacked ubuntu.sh using script from PX4 v1.15.4 to support Ubuntu 24.04
  2. setup a python virtual environment - I accept your advice that this is not necessary - but this was before I got your reply, and i don’t like python3 -m pip install --break-system-packages.
    python3 -m venv ./pyenv
    source /.pyenv/activate
    pip install --upgrade pip
    bash ./Tools/setup/ubuntu.sh
    – install various missing requirements
    Restart computer
    Start QgroundControl
    cd ~/PX4-Autopilot-1.15.2/Firmware
    source ./pyenv/bin/activate
    make px4_sitl gz_x500
    ======== RESULT 1 =============
    ….
    WARN [init] PX4_GZ_MODEL_POSE not set, spawning at origin.
    INFO [gz_bridge] world: default, model name: x500_0, simulation model: x500
    INFO [gz_bridge] Requested Model Position: 0,0,0,0,0,0
    INFO [gz_bridge] Model position z is less or equal 0.0, moving upwards
    ERROR [gz_bridge] Service call timed out. Check GZ_SIM_RESOURCE_PATH is set correctly.
    ERROR [gz_bridge] Task start failed (-1)
    ERROR [init] gz_bridge failed to start and spawn model
    ERROR [init] gz_bridge failed to start and spawn model
    ERROR [px4] Startup script returned with return value: 256
    libEGL warning: egl: failed to create dri2 screen
    libEGL warning: egl: failed to create dri2 screen
    libEGL warning: egl: failed to create dri2 screen
    ^Cninja: build stopped: interrupted by user.
    make: *** [Makefile:232: px4_sitl] Interrupt
    === give it another kick =================================
    make px4_sitl gz_x500
    ======== RESULT 2 =============
    ….
    pxh> INFO [commander] Ready for takeoff!
    pxh> commander takeoff
    pxh> INFO [commander] Armed by internal command
    INFO [tone_alarm] arming warning
    INFO [navigator] Using default takeoff altitude: 2.5 m
    INFO [commander] Takeoff detected
    pxh> commander land
    pxh> INFO [commander] Landing at current position
    INFO [commander] Landing detected
    INFO [commander] Disarmed by landing
    INFO [tone_alarm] notify neutral

==================================================

6

Ok I suppose you mean the version can clone as in Building PX4 Software | PX4 Guide (main)
I did that:
$ git status
On branch main
Your branch is up to date with ‘origin/main’
and I see a commit yesterday Date: Fri Mar 14 16:25:28 2025 +0100

I will try that

7

So I tried the version I cloned at
([Building PX4 Software | PX4 Guide (main)]
with hacks as for PX4 v1.15.2 (see above and below)

This built without error ( as far as I know) but the result is similar to the failure of PX4 v1.15.4
Looks like it produced a much improved UI for gazebo.
But my hack of PX4 v1.15.2 (see above) seems to actually fly.
Don

make px4_sitl gz_x500
======== RESULT =============
…
CMake Deprecation Warnings
…

| ___ \ \ \ / / / |
| |/ / \ V / / /| |
| __/ / \ / /| |
| | / /^\ \ ___ |
_| / / |_/

px4 starting.
…
INFO [px4] Startup script returned successfully
pxh> WARN [health_and_arming_checks] Preflight Fail: No connection to the ground control station
INFO [commander] Ready for takeoff!
ERROR [sensors] Accel #0 fail: TIMEOUT!
WARN [health_and_arming_checks] Preflight Fail: vertical velocity unstable
ERROR [sensors] Accel #0 fail: TIMEOUT!
WARN [health_and_arming_checks] Preflight Fail: vertical velocity unstable
pxh> commWARN [health_and_arming_checks] Preflight Fail: vertical velocity unstable
WARN [health_and_arming_checks] Preflight Fail: High Accelerometer Bias
pxh> commander WARN [health_and_arming_checks] Preflight Fail: High Accelerometer Bias
pxh> commander takeoff
pxh> WARN [commander] Arming denied: Resolve system health failures first
INFO [tone_alarm] notify negative
ERROR [sensors] Accel #0 fail: TIMEOUT!
ERROR [sensors] Accel #0 fail: TIMEOUT!
ERROR [sensors] Accel #0 fail: TIMEOUT!
ERROR [sensors] Accel #0 fail: TIMEOUT!

======== HACKS =============
As with PX4 v1.15.2 I hacked
./Tools/setup/requirements.txt:
DELETE LINE ( matplotlib>=3.0.* )`

./Tools/setup/ubuntu.sh
DELETE
if
[[ “$(printf ‘%s\n’ “$REQUIRED_VERSION”
“$PYTHON_VERSION” | sort -V | head -n1)” ==
“$REQUIRED_VERSION” ]]; then`
python3 -m pip install --break-system-packages -r ${DIR}/requirements.txt
else

fi

And used a virtual environment for python as above
python3 -m venv ./pyenv
8

the same issue.
refer to: ERROR [sensors] Accel #0 Fail: TIMEOUT!