2.0.0rc1 Bambu A1: module 'paho.mqtt.client' has no attribute 'CallbackAPIVersion'

[St-Aris]

The problem

Installed 2.0.0rc1
Installed Bambu A1 0.0.1 connector
Get error when attempted to connect:

Queue:
State: Offline after error
module 'paho.mqtt.client' has no attribute 'CallbackAPIVersion'

Did the issue persist even in safe mode?

I cannot test this issue in safe mode (state why below)

If you could not test in safe mode, please state why ("currently printing" is NOT an excuse!)

Irrelevant

Version of OctoPrint

2.0.0rc1

Operating system running OctoPrint

OctoPi

Browser and version of browser, operating system running browser

Firefox - macos

Printer model & used firmware incl. version

Bambu A1 1.03.30.01 (not the latest!)

Systeminfo Bundle

octoprint-systeminfo-20260428153300.zip¹

Checklist of files to include below

• Contents of the JavaScript browser console (always include in cases of issues with the user interface)
• Screenshots and/or videos showing the problem (always include in case of issues with the user interface)
• GCODE file with which to reproduce (always include in case of issues with GCODE analysis or printing behaviour)

Additional information & file uploads

Did a quick search:

The error "module 'paho.mqtt.client' has no attribute 'CallbackAPIVersion'" occurs when your code tries to access CallbackAPIVersion (typically in a line like mqtt.Client(mqtt.CallbackAPIVersion.VERSION1)), but the installed paho-mqtt library version doesn't export it from that module.

Footnotes

1. octoprint-systeminfo-20260428153300.zip (bundleviewer) (download)
   OctoPrint: 2.0.0rc1
   Python: 3.11.2
   OS: Linux-6.12.25+rpt-rpi-v7-armv7l-with-glibc2.36
   RPi: Raspberry Pi 2 Model B Rev 1.1
   OctoPi: 1.1.0 (build 2025.05.13.134411)
   Browser: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:150.0) Gecko/20100101 Firefox/150.0 ↩

[foosel]

After some research, please try manually upgrading the version of paho-mqtt installed in your virtual environment (pip install paho-mqtt>2), you probably have some 1.x version (maybe from a former installation of the mqtt plugin?) and need 2.x for the connector. I've sent a PR to the bambu library we use in the connector plugin to get that added there: synman/bambu-printer-manager#53

[St-Aris]

Tried that:

root@octopi:/opt/octopi/scripts# pip install paho-mqtt
error: externally-managed-environment

This environment is externally managed
To install Python packages system-wide, try apt install
python3-xyz, where xyz is the package you are trying to
install.

If you wish to install a non-Debian-packaged Python package,
create a virtual environment using python3 -m venv path/to/venv.
Then use path/to/venv/bin/python and path/to/venv/bin/pip. Make
sure you have python3-full installed.

For more information visit http://rptl.io/venv

note: If you believe this is a mistake, please contact your Python installation or OS distribution provider. You can override this, at the risk of breaking your Python installation or OS, by passing --break-system-packages.
hint: See PEP 668 for the detailed specification.

I ended up doing a: apt install python3-paho-mqtt

I'm running octopi 1.1.0

I restarted Octoprint - but still doesn't work. Now it says:

Queue: Inactive (active print continues unmanaged)
State: Offline after error
module 'paho.mqtt.client' has no attribute 'CallbackAPIVersion'

[foosel]

Sorry, should have clearer...

It needs to be run in your virtual environment, on OctoPi 1.1.0 that is /opt/octoprint, so /opt/octoprint/bin/pip install "paho-mqtt>2" if I remember correctly.

[St-Aris]

Just an addendum - it appears to be an old version:

python3-paho-mqtt/oldstable,now 1.6.1-1 all [installed]

[St-Aris]

So I did it in the environment:

/opt/octopi/oprint/bin/pip install paho-mqtt
Looking in indexes: https://pypi.org/simple, https://www.piwheels.org/simple
Requirement already satisfied: paho-mqtt in /opt/octopi/oprint/lib/python3.11/site-packages (1.6.1)

Sounds like i need to find a pip for 2.x of this package.

[foosel]

You forgot something there, I explicitly added >2 at the end for a reason ;)

/opt/octopi/oprint/bin/pip install "paho-mqtt>2"

[St-Aris]

You are right :)

paho-mqtt 2.1.0

I had to restart Octoprint - but it looks like it is connected!

Perhaps the paho-mqtt is something you can check for during the upgrade (or installation of the connector).

I started a print job from the printer itself, and it seems to be picking up the temperatures. Also picking up the state (initialising, homing, printing, etc). Estimated print time seems to be there too - and it matches the printer screen.

Question now is - how do I use it in other ways? Can I print via octoprint from Orca Slicer - and will it support the AMS?

[foosel]

Perhaps the paho-mqtt is something you can check for during the upgrade (or installation of the connector).

That's what is already in the works in the aforementioned PR: synman/bambu-printer-manager#53

Question now is - how do I use it in other ways? Can I print via octoprint from Orca Slicer - and will it support the AMS?

That's the goal here.

[St-Aris]

So for the time being - it is just monitoring print status? No other features I can test?

[foosel]

Starting prints, pausing prints, stopping prints, file management, thumbnail visualisation, starting prints through OctoPrint, uploading files through OctoPrint, plugins listening to print events getting triggered, ...

In short, most of what is possible via serial should also already work here. AMS is something I haven't yet tested much apart from selecting the filament to use for a print job, I don't know how much @jneilliii tested there, most likely more (as I was busy with stock OctoPrint and the Moonraker connector).

[St-Aris]

I can confirm that Octopod push notifications on completion of a print works - which is just amazing!

[foosel]

That's some great news :D Third party clients might still need to do some work to be able to work with the new connector approach, so you probably cannot connect from that yet, but other than that most things should just work I hope...