Connot connect to Prusa I3 MKS after upgrading to 1.4.2

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1

What is the problem?

OctoPrint has been working successfully with my Prusa I3 MK3S for several months. A few days ago OctoPrint stopped connecting to the MKS. It gets stalled at "opening serial connection".

What did you already try to solve it?

I recreated a system image from Octopi_buster_lite_0.17.0.
The system worked successfully. Since I had previously updated the s/w to 1.4.2 and was using it successfully I updated again to 1.4.2
The problem reappeared.
I have no plugins except those tha are bundled with the update.

Have you tried running in safe mode and if so did it solve the issue?

After starting up in safe mode the serial connection to the printer is made successfully.
After rebooting in normal mode the problem reappears

Complete Logs

I don't know how to get the serial.log off the Rpi but it looks like the following screen grab from by browser:
Changing monitoring state from "Offline" to "Detecting serial connection"
Performing autodetection with 7 port/baudrate candidates: /dev/ttyACM0@115200, /dev/ttyACM0@250000, /dev/ttyACM0@230400, /dev/ttyACM0@57600, /dev/ttyACM0@38400, /dev/ttyACM0@19200, /dev/ttyACM0@9600
Trying port /dev/ttyACM0, baudrate 115200
Connecting to port /dev/ttyACM0, baudrate 115200
Handshake attempt #1 with timeout 2.0s
Connected to: Serial<id=0xae9d5a70, open=True>(port='/dev/ttyACM0', baudrate=115200, bytesize=8, parity='N', stopbits=1, timeout=2.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 250000
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 230400
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 57600
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 38400
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 19200
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0125
Trying port /dev/ttyACM0, baudrate 9600
Handshake attempt #1 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #2 with timeout 2.0s
Send: N0 M110 N0125
Handshake attempt #3 with timeout 2.0s
Send: N0 M110 N0*125
Changing monitoring state from "Detecting serial connection" to "Error: No more candidates to test, and no working port/baudrate combination detected."
Changing monitoring state from "Error: No more candidates to test, and no working port/baudrate combination detected." to "Offline (Error: No more candidates to test, and no working port/baudrate combination detected.)"
Connection closed, closing down monitor

Here is a log:
2020-09-26 terminal 1-05.txt.zip (1.3 KB)

Additional information about your setup

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

Running OctoPrint (version 1.4.2 is causing the problem) with no plugins except for what is bundled with 1.4.2
Raspberry pi 4B
Prusa I3 MKS
accessing octoprint.local from Firefox browser on MacBook

2

You see that word serial.log is in blue? It's a link :wink:

Already installed the recent firmware from Prusa (V 3.9.1)?
According the data you provided, the is no reaction of the printer at all.
Is it switched on? Is USB cable proper connected?
Can you connect to the printer with pronterface?

3

Thank you for the quick reply. No I am not using Prusa V 3.9.1, just 3.9.0-3421 so I will try that.
btw Pretty sure that the cable is good because when I toggle between safe mode and normal mode OctoPrint connects is safe mode.

4

When it works in safemode, then an installed 3rd party plugin seems to be the issue.
You may disable them all or just those that may effect the serial connection. You also may share a list of the plugins you use.

5

Thanks once again. No plugins except those that were bundled with 1.4.2. That is what confused me.
Still working on the firmware update for MKS. If that solves the prob will mark problem solved.

1 Like
6

Upgrading the firmware on the printer resolved the problem. Thanks again for your help

1 Like