Prusa MK3s + MMU2s don't connect to Octoprint


i have a Prusa i3 MK3S (v. MMU2s (v.1.0.6) and a OctoPrint (v.1.4.0)/ OctoPi (v.0.15.0PE)

What is the problem?

I'm unable to connect printer to Octoprint via RPI port.

Could you please help me ?

What did you already try to solve it?

It worked without MMU2S module
Tried Safe-mode but doesn't work.
RPI port turned ON on Prusa printer. Turned OFF and ON
Removed SD card
Completely reboot printer.

Logs (syslog, dmesg, ... no logs, no support)

Serial port : dev/ttyAMAO
Baudrate : 115200
Printer profiles : 5 extruders / Shared Nozzle

Connecting to: /dev/ttyAMA0
Changing monitoring state from "Offline" to "Opening serial port"
Connected to: Serial<id=0xafb76d10, open=True>(port='/dev/ttyAMA0', baudrate=115200, bytesize=8, parity='N', stopbits=1, timeout=10.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor
Changing monitoring state from "Opening serial port" to "Connecting"
There was a timeout while trying to connect to the printer
Changing monitoring state from "Connecting" to "Offline"
Connection closed, closing down monitor

octoprint.log (56.0 KB) serial.log (697 Bytes)

Additional information about your network (Hardware you are trying to connect to, hardware you are trying to connect from, router, access point, used operating systems, ...)

Hello @3iiko!

Short question: does the MMU2S work properly with the Pi Zero installed (print from SD card)?

You may install the most recent version of OctoPi (0.17.0)

It's also recommended to use a RasPi 3B. Prusa's RasPi Zero W solution is hard on the edge concerning it's abilities.


thak you for your response.

Yes, it's printing with the PI installed from the SD card directly.

How to update OctoPi ?

I ordered a Pi 4, is it working with OctoPrint ?


Easy: You get the recent OctoPi image from here: - Download & Setup OctoPrint
You can find all the steps to install OctoPi there too.

You may make a backup of all the things you installed to OctoPrint and store it to your PC. When OctoPrint is running, you can use the backup file to get the plugins back to your OctoPrint.

When you get your new Pi 4, you can just swap the SD card from the Zero to the 4. Take care to use a goof USB cable and a proper power adaper for the Pi 4 - not a charger.

Thank you for your help.

I reinstall the good OctoPrint version then configure follow the instruction on the link you gave me and it work. The printer connects !!

I have few question, can i update to OctoPrint 1.4.0 without issue ? Currently the version is 1.3.12.

Also you tell me to buy a good USB cable and proper power adapter ? Do you have some link ? I'm new with Raspberry and i don't know exactly what i need to run the Pi 4 on Prusa.

Thank you again for your precious help.

Update to 1.4.0 should work fine.
For the USB cable look for a thicker one, one that is proper shielded and has ferrite beads on it. And as short as necessary. Like this:
For the power adaper most recommended is the original one: