"Printer reset detected" warning


What is the problem?
I am getting a warning " Printer reset detected" (It looks like your printer reset while a connection was active. If this was intentional you may safely ignore this message. Otherwise you should investigate why your printer reset itself, since this will interrupt prints and also file transfers to your printer's SD.)

What did you already try to solve it?
I uninstalled the plug ins that I really didn't need and hope for the best.

Additional information about your setup (OctoPrint version, OctoPi version, printer, firmware, octoprint.log, serial.log or output on terminal tab, ...)

Ocotprint Version 1.3.9
Octopi 0.15.1


Did you get that message by accident or did your printer actually reset?


The message just popped out.
I am a brand new user. I am not even sure how to reset it.


"Reset" here means that its controller restarted. Usually that happens when you power cycle your printer for example. OctoPrint detects this since firmware will (well... is supposed to) send a start over serial when booting up, and if OctoPrint sees that while it's already connected to your printer it assumes something is off since usually it never should get such a message from a powered on printer and hence notifies the user.

If you had shared a serial.log or at least the contents of your Terminal tab from when it happened plus your octoprint.log we might be able to analyse this further and help you determining the cause, but you sadly haven't.


Gina sorry,
I am a super new user and last night I could not figure out where those log files were located (3.0 KB)
. My learning curve is so steep that my head is spinning all day. Anyways
Here they are.
serial.log (7.2 KB)
octoprint.log (378.6 KB)

I am using a Prusa MK3 with a freshly flashed 3.4.0 firmware (not sure if this helps)

I hope this will help..
thanks in advance


Looks like a firmware bug. That printer is sending the start line twice instead of once:

2018-09-21 11:43:03,294 - Changing monitoring state from "Offline" to "Detecting serial port"
2018-09-21 11:43:03,357 - Serial port list: ['/dev/ttyACM0']
2018-09-21 11:43:03,357 - Connecting to: /dev/ttyACM0
2018-09-21 11:43:03,366 - Changing monitoring state from "Detecting serial port" to "Opening serial port"
2018-09-21 11:43:03,370 - Connected to: Serial<id=0x6daafc10, open=True>(port='/dev/ttyACM0', baudrate=115200, bytesize=8, parity='N', stopbits=1, timeout=10.0, xonxoff=False, rtscts=False, dsrdtr=False), starting monitor
2018-09-21 11:43:03,371 - Starting baud rate detection...
2018-09-21 11:43:03,371 - Changing monitoring state from "Opening serial port" to "Detecting baudrate"
2018-09-21 11:43:04,380 - Trying baudrate: 115200
2018-09-21 11:43:04,404 - Send: N0 M110 N0*125
2018-09-21 11:43:04,713 - Recv: start
2018-09-21 11:43:04,717 - Changing monitoring state from "Detecting baudrate" to "Operational"
2018-09-21 11:43:04,729 - Recv: start
2018-09-21 11:43:04,732 - Printer sent 'start' while already operational. External reset? Resetting line numbers to be on the safe side
2018-09-21 11:43:04,733 - Send: N1 M105*38

Note the first start received at 2018-09-21 11:43:04,713 and then the second right after at 2018-09-21 11:43:04,729. The second one shouldn't be there.

My own MK3 with an older firmware doesn't have that issue, so money would be on that bug crept in in a recent release, maybe even only in 3.4.0. I suggest you open a ticket on the Prusa Firmware issue tracker. Feel free to link that ticket here and I'll weigh in on it. Meanwhile this isn't causing any issues and you can safely ignore that warning until the bug is fixed in the firmware.


Here we go.

Thanks your prompt response.


There is a new firmware 3.4.1 that fixes this issue