Serial exception - printer randomly stops midprint


Octoprint was working flawlessly and now it randomly disconnects and the print stops.

Ender 3 with latest Marlin firmware connected to a raspberry pi 3b with genuine power supply running latest Octopi firmware and Pi cam. Tried reboots and different USB cable.
Please help, I love this program!

What to do next? fresh install? this install has only been in a few weeks.

octoprint.log (12.6 KB)


Hi @westford1394,

already followed the link in your log file?

2019-01-18 18:13:57,783 - octoprint.util.comm - ERROR - Please see for possible reasons of this.


Hi Ewald

Yes everything on the list but the last bullet point - I don't know what this dwc_otg.speed=1 to /boot/cmdline.txt means and as it was working fine without doing the above, I'm not sure why things have changed?


I see,
could you then also provide the serial.log. In this case it is most informative.
If it s empty, you may have to start serial logging.


You are right, it's not enabled, I will enable it and run another print - might not be able to do this until later on tomorrow though. Many thanks for your help so far!


I Haven't got a serial log of any use yet but I have found out something interesting! A well known thing on the Ender 3 and probably others is that the 5V from the USB of the Pi powers the mainboard of the printer when the printer is turned off from the mains and many people including me use a TP link mains socket to turn off the printer when it has finished. The way around the Pi powering the mainboard is to insulate the 5V pin on the USB so their is no power supplied to the mainboard when it is powered down. It turns out that in my case if I don't insulate the 5V pin the print runs perfectly but if I insulate it I will more often than not disconnect from the Pi while printing. The question is why is this the case and how can I get around this - there is something odd happening!