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

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):
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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:>S1
ad.
Recv: echo:MMU2:<S1 A034.
Recv: echo:MMU2:>S2
10.
Recv: echo:MMU2:<S2 A15a.
Recv: echo:MMU2:>S3
7b.
Recv: echo:MMU2:<S3 A34575.
Recv: echo:MMU2:>Wb 5
33.
Recv: echo:MMU2:<Wb A5c.
Recv: echo:MMU2:>W14 14
94.
Recv: echo:MMU2:<W14 A52.
Recv: echo:MMU2:>f0
21.
Recv: echo:MMU2:<f0 Ac5.
Recv: echo:MMU2:>Q0
ea.
Recv: echo:MMU2:<X0 F087.
Recv: echo:MMU2:>R8
81.
Recv: echo:MMU2:<R8 A08d.
Recv: echo:MMU2:>R1b
9e.
Recv: echo:MMU2:<R1b Affbf.
Recv: echo:MMU2:>R1c
88.
Recv: echo:MMU2:<R1c Aff60.
Recv: echo:MMU2:>R4
7b.
Recv: echo:MMU2:<R4 A2860.
Recv: echo:MMU2:>R1a
f5.
Recv: echo:MMU2:<R1a A041.
Recv: echo:MMU2:>Q0
ea.
Recv: echo:MMU2:<X0 F087.
Recv: echo:MMU2:>R8
81.
Recv: echo:MMU2:<R8 A08d.
Recv: echo:MMU2:>R1b
9e.
Recv: echo:MMU2:<R1b Affbf.
Recv: echo:MMU2:>R1c
88.
Recv: echo:MMU2:<R1c Aff60.
Recv: echo:MMU2:>R4
7b.
Recv: echo:MMU2:<R4 A2860.
Recv: echo:MMU2:>R1a
f5.
Recv: echo:MMU2:<R1a A041.
Recv: echo:MMU2:>Q0
ea.
Recv: echo:MMU2:<X0 F087.
Recv: echo:MMU2:>R8
81.
Recv: echo:MMU2:<R8 A08d.
Recv: echo:MMU2:>R1b
9e.
Recv: echo:MMU2:<R1b Affbf.
Recv: echo:MMU2:>R1c
88.
Recv: echo:MMU2:<R1c A5f6.
Recv: echo:MMU2:>R4
7b.
Recv: echo:MMU2:<R4 A2860.
Recv: echo:MMU2:>R1a
f5.
Recv: echo:MMU2:<R1a A041.
Recv: echo:MMU2:>Q0
ea.
Recv: echo:MMU2:<X0 F087.
Recv: echo:MMU2:>R8
81.
Recv: echo:MMU2:<R8 A08d.
Recv: echo:MMU2:>R1b
9e.
Recv: echo:MMU2:<R1b Affbf.
Recv: echo:MMU2:>R1c
88.
Recv: echo:MMU2:<R1c A5f6.
Recv: echo:MMU2:>R4
7b.
Recv: echo:MMU2:<R4 A2860.
Recv: echo:MMU2:>R1a
f5.
Recv: echo:MMU2:<R1a A0*41.
Connection closed, closing down monitor
Changing monitoring state from "Connecting" to "Offline"

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