Octoprint 1.11.0 stuck on "Connecting" when connecting to Prusa MK3S

piranha32 · April 30, 2025, 5:31pm

What is the problem?

After upgrade to Octoprint 1.11.0 from 1.10.(?) I can no longer connect to the printer. The serial port opens properly, there is active communication between printer and Octoprint, but the connection never advances to "Connected" state.

What did you already try to solve it?

Restart Octoprint
Restart the host computer
Restart the printer
Restart the printer and the host computer
Restart Octoprint in Safe Mode

Have you tried running in safe mode?

Yes

Did running in safe mode solve the problem?

No

Systeminfo Bundle

You can download this in OctoPrint's System Information dialog ... no bundle, no support!)

octoprint-systeminfo-20250430121325.zip (105.3 KB)

Additional information about your setup

OctoPrint version, OctoPi version, printer, firmware, browser, operating system, ... as much data as possible

Octoprint version: 1.11.0
Host OS version: Build 2023.07.20.144556 with "camera-streamer", based on OctoPi 1.0.0, running on Raspberry Pi 3 Model B Plus Rev 1.3
Printer firmware version: 3.13.2-7080
MMU firmware version: 3.0.1

Log of serial port communication during connection attempt (closed manually, it can go on and on indefinitely):
---- cut here ----
Recv: echo: Last Updated: Oct 20 2023 17:49:53 | Author: (none, default config)
Recv: echo: Free Memory: 2513 PlannerBufferBytes: 1760
Recv: echo:Stored settings retrieved
Recv: adc_init
Recv: Hotend fan type: NOCTUA
Recv: CrashDetect ENABLED!
Recv: Sending 0xFF
Recv: echo:SD card ok
Recv: // action:dump_available
Recv: echo:MMU2:<S0 A322.
Recv: echo:MMU2:>S1ad.
Recv: echo:MMU2:<S1 A034.
Recv: echo:MMU2:>S210.
Recv: echo:MMU2:<S2 A15a.
Recv: echo:MMU2:>S37b.
Recv: echo:MMU2:<S3 A34575.
Recv: echo:MMU2:>Wb 533.
Recv: echo:MMU2:<Wb A5c.
Recv: echo:MMU2:>W14 1494.
Recv: echo:MMU2:<W14 A52.
Recv: echo:MMU2:>f021.
Recv: echo:MMU2:<f0 Ac5.
Recv: echo:MMU2:>Q0ea.
Recv: echo:MMU2:<X0 F087.
Recv: echo:MMU2:>R881.
Recv: echo:MMU2:<R8 A08d.
Recv: echo:MMU2:>R1b9e.
Recv: echo:MMU2:<R1b Affbf.
Recv: echo:MMU2:>R1c88.
Recv: echo:MMU2:<R1c Aff60.
Recv: echo:MMU2:>R47b.
Recv: echo:MMU2:<R4 A2860.
Recv: echo:MMU2:>R1af5.
Recv: echo:MMU2:<R1a A041.
Recv: echo:MMU2:>Q0ea.
Recv: echo:MMU2:<X0 F087.
Recv: echo:MMU2:>R881.
Recv: echo:MMU2:<R8 A08d.
Recv: echo:MMU2:>R1b9e.
Recv: echo:MMU2:<R1b Affbf.
Recv: echo:MMU2:>R1c88.
Recv: echo:MMU2:<R1c Aff60.
Recv: echo:MMU2:>R47b.
Recv: echo:MMU2:<R4 A2860.
Recv: echo:MMU2:>R1af5.
Recv: echo:MMU2:<R1a A041.
Recv: echo:MMU2:>Q0ea.
Recv: echo:MMU2:<X0 F087.
Recv: echo:MMU2:>R881.
Recv: echo:MMU2:<R8 A08d.
Recv: echo:MMU2:>R1b9e.
Recv: echo:MMU2:<R1b Affbf.
Recv: echo:MMU2:>R1c88.
Recv: echo:MMU2:<R1c A5f6.
Recv: echo:MMU2:>R47b.
Recv: echo:MMU2:<R4 A2860.
Recv: echo:MMU2:>R1af5.
Recv: echo:MMU2:<R1a A041.
Recv: echo:MMU2:>Q0ea.
Recv: echo:MMU2:<X0 F087.
Recv: echo:MMU2:>R881.
Recv: echo:MMU2:<R8 A08d.
Recv: echo:MMU2:>R1b9e.
Recv: echo:MMU2:<R1b Affbf.
Recv: echo:MMU2:>R1c88.
Recv: echo:MMU2:<R1c A5f6.
Recv: echo:MMU2:>R47b.
Recv: echo:MMU2:<R4 A2860.
Recv: echo:MMU2:>R1af5.
Recv: echo:MMU2:<R1a A0*41.
Connection closed, closing down monitor
Changing monitoring state from "Connecting" to "Offline"

---- cut here ----

wseifert · May 6, 2025, 10:19am

Same to me on both of my Prusa printers. Had to revert to 1.10 ...

Ewald_Ikemann · May 6, 2025, 12:17pm

The log excerpt looks fine to me. These are the frequent MMU information from the printer.
It tells me, that the connection is established.

You can suppress these messages by

piranha32 · May 6, 2025, 3:38pm

I submitted a bug report at github. The devs said that it'd be difficult for them to reproduce the bug, so I think it could be helpful if you could confirm it, with system info from your setup. Just don;t forget to enable serial port logging to capture communication between octoprint and the printer before generating the system info bundle

github.com/OctoPrint/OctoPrint

Octoprint 1.11.0 stuck on "Connecting" when connecting to Prusa MK3S with uBlock origin active

opened 04:44PM - 01 May 25 UTC

piranha32

triage

### The problem After upgrade to Octoprint 1.11.0 from 1.10.(?) I can no longer… connect to the printer. The serial port opens properly, there is active communication between printer and Octoprint, but the connection never advances to "Connected" state. Log of serial port communication during connection attempt (closed manually, it can go on and on indefinitely): [2025-04-30_octoprint_prusa_serial_comms.txt](https://github.com/user-attachments/files/20001491/2025-04-30_octoprint_prusa_serial_comms.txt) I tried: - Restart Octoprint - Restart the host computer - Restart the printer - Restart the printer and the host computer - Restart Octoprint in Safe Mode - Disabling uBlock Origin *Sometimes* connection succeeds in safe mode with uBlock Origin disabled, but I could not identify the combination of operations to make it reproducible. Screenshots of browser console and network traffic with uBlock disabled attached. ![Image](https://github.com/user-attachments/assets/917cec53-586f-446b-b1c4-8ede39842127) ![Image](https://github.com/user-attachments/assets/5fca1d5d-b760-480b-ab16-4218d600c385) ### Did the issue persist even in safe mode? Yes, it did persist ### If you could not test in safe mode, please state why ("currently printing" is NOT an excuse!) N/A ### Version of OctoPrint 1.11.0 ### Operating system running OctoPrint Build 2023.07.20.144556 with "camera-streamer", based on OctoPi 1.0.0, running on Raspberry Pi 3 Model B Plus Rev 1.3 ### Browser and version of browser, operating system running browser Firefox, Fedora 41 ### Printer model & used firmware incl. version Prusa MK3S, Printer firmware version: 3.13.2-7080, MMU firmware version: 3.0.1 ### Checklist of files to include below - [x] Systeminfo Bundle (always include!) - [x] Contents of the JavaScript browser console (always include in cases of issues with the user interface) - [x] 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 [octoprint-systeminfo-20250430121325.zip](https://github.com/user-attachments/files/20001498/octoprint-systeminfo-20250430121325.zip)[^bundle1] [^bundle1]: `octoprint-systeminfo-20250430121325.zip` ([bundleviewer](https://bundleviewer.octoprint.org/?url=https%3A%2F%2Fgithub.com%2Fuser-attachments%2Ffiles%2F20001498%2Foctoprint-systeminfo-20250430121325.zip)) ([download](https://github.com/user-attachments/files/20001498/octoprint-systeminfo-20250430121325.zip)) **OctoPrint**: 1.11.0 **Python**: 3.9.2 **OS**: Linux-6.1.21-v7+-armv7l-with-glibc2.31 **RPi**: Raspberry Pi 3 Model B Plus Rev 1.3 **OctoPi**: 1.0.0cam (build 2023.07.20.144556) **Browser**: Mozilla/5.0 (X11; Linux x86_64; rv:137.0) Gecko/20100101 Firefox/137.0

foosel · May 13, 2025, 10:40am

The issue has hopefully been identified and a bugfix release is incoming ASAP. In the meantime, it might help to enable "wait for start on connect" in the serial settings under firmware & protocol.

beevo · May 14, 2025, 12:11am

I have three printers running Octoprint.

All of a sudden all three will not connect, OctoPi starts just find but the printers never are detected. All three are running the latest release.

I find this kinda suspicious, thoughts?

Ewald_Ikemann · May 14, 2025, 3:07am

At this moment, "latest" release is V 1.11.1, you are posting to a thread that refers to 1.11.0. So what what version do you have?

piranha32 · May 14, 2025, 3:10am

Downgrade manually to 1.10.3 or help testing 1.11.1, which is supposed to fix this issue.
If you don't want to do any of these, you can try enabling "wait for start on connect"