Commands are ignored until i press "fake acknowledgement"

What is the problem?

ODROID c1+, self installed
After connecting OCTOPRINT with my Ender 3, octoprint get some information about the printer, and than it stuck and (maybe) waiting for a "ok"

What did you already try to solve it?

Giving the user tty and dialout groups

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


Complete Logs

octoprint.log, serial.log or output on terminal tab at a minimum, browser error console if UI issue ... no logs, no support! Not log excerpts, complete logs.)

2020-11-08 13:39:33,334 - Changing monitoring state from "Offline" to "Detecting serial connection"
2020-11-08 13:39:33,532 - Performing autodetection with 3 port/baudrate candidates: /dev/ttyACM0@250000, /dev/ttyS2@250000, /dev/ttyS0@250000
2020-11-08 13:39:33,534 - Trying port /dev/ttyACM0, baudrate 250000
2020-11-08 13:39:33,536 - Connecting to port /dev/ttyACM0, baudrate 250000
2020-11-08 13:39:33,545 - Handshake attempt #1 with timeout 2.0s
2020-11-08 13:39:33,549 - Connected to: Serial<id=0xac11b208, open=True>(port='/dev/ttyACM0', baudrate=250000, bytesize=8, parity='N', stopbits=1, timeout=2.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor
2020-11-08 13:39:33,551 - Send: N0 M110 N0125
2020-11-08 13:39:33,558 - Recv: ok
2020-11-08 13:39:33,606 - Changing monitoring state from "Detecting serial connection" to "Operational"
2020-11-08 13:39:33,620 - Send: N0 M110 N0
2020-11-08 13:39:33,656 - Recv: ok
2020-11-08 13:39:33,659 - Send: N1 M115*39
2020-11-08 13:39:33,687 - Recv: FIRMWARE_NAME:Marlin bugfix-2.0.x (Github) SOURCE_CODE_URL: PROTOCOL_VERSION:1.0 MACHINE_TYPE:SKR-mini-E3-V1.2 EXTRUDER_COUNT:1 UUID:cede2a2f-41a2-4748-9b12-c55c62f367ff
2020-11-08 13:39:33,691 - Recv: Cap:SERIAL_XON_XOFF:0
2020-11-08 13:39:33,692 - Recv: Cap:BINARY_FILE_TRANSFEap:SOFTWARE_POWER:0
2020-11-08 13:39:33,694 - Recv: Cap:TOGGLE_LIGHTS:0

  • I PRESS FAKE OK * (M105)
    2020-11-08 13:39:52,667 - Recv: Cap:CASE_LIGHT_BRIGHTNok T:20.62 /0.00 B:20.62 /0.00 @:0 B@:0
    2020-11-08 13:39:54,991 - Send: G91
    2020-11-08 13:39:55,001 - Recv: ok
    2020-11-08 13:39:55,003 - Send: G28 X0 Y0

no it works without any issues

Additional information about your setup

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

Pyhton 3.8.5
Octoprint 1.4.2
Odroid c1+
Ender 3 (SKR MINI)
Printer firmware see in log

That ok stuff should be on its own line. The way it is now it is not a proper acknowledgement and without a proper acknowledgement OctoPrint must not continue to send any commands to the printer.

Could be either some issue with your cable (though weird that it only causes issues on initial connect) or a firmware bug.

This however:

2020-11-08 13:39:33,692 - Recv: Cap:BINARY_FILE_TRANSFEap:SOFTWARE_POWER:0

makes the cable/connection issue more likely, or maybe a weird issue with the serial driver overwriting its receiving buffers, as those also should be two lines.

Something in your printer communication is broken and needs fixing. OctoPrint can't really operate with a printer that doesn't adhere to the de-facto protocol.


but the cable is the same. I had a RPi2B working on it and it was without any problems...

Maybe the ODROID have a problem with its driver or something similar...
Should i switch to the old raspberry?

I would at least suggest to try if the issue still reproduces with a Pi or not. The thing is, these kind of issues are hard to debug remotely, so it sadly requires some testing-out-stuff-and-seeing-where-it-gets-you on your side.

All I can tell you definitely is that the lines that OctoPrint receives from your printer arrive garbled, and that happens outside of OctoPrint's control, either on driver, hardware or firmware level.