Printer immediately disconnects when print starts with SerialException: device reports readiness to read but returned no data (device disconnected or multiple access on port?)

[Alexander_Kanev]

What is the problem?

I started setting up octoprint this morning because I found my old RPI 3B Last night and recently got an Ender 3 V2 for Christmas. However, when I try to print a file the printer immediately disconnects and also seems to reboot. Octoprint is saying that my PI is undervolted however the red light is static which means that it shouldn't be undervolted. I use a charger for the RPI which does 5V with 3A which I believe would be sufficient but I don't know for sure. So do I need a new power supply?
While making this post the printer also started to randomly make a weird wiring noise and only stopped when I unplugged it from the RPI. I have no idea whether this is something related to this or not.

What did you already try to solve it?

Changing USB ports and cables

Have you tried running in safe mode?

Yes

Did running in safe mode solve the problem?

No

Systeminfo Bundle

octoprint.log (370.6 KB)
serial.log (1.0 KB)

Additional information about your setup

OctoPrint version 1.9.3, OctoPi version 1.0.0, printer: Ender3 V2, firmware: Marlin 2.0.8, browser: Opera GX and Chrome, Raspberry PI 3B, webcam: Logitech C920

[Ewald_Ikemann]

Hello @Alexander_Kanev !

@Alexander_Kanev

however the red light is static which means that it shouldn't be undervolted

The read light just indicates that there is power. It does not tell anything about the quality.

Your Pi is definitely underpowered:

2024-01-17 15:11:49,610 - octoprint.plugins.pi_support - WARNING - This Raspberry Pi is reporting problems that might lead to bad performance or errors caused by overheating or insufficient power.
!!! UNDERVOLTAGE REPORTED !!! Make sure that the power supply and power cable are capable of supplying enough voltage and current to your Pi.

---

For you have a Creality printer, try with/without SD card in the printer's SD card slot.

Also try.

Put tape on the 5V pin - Why and how

First of all this whole tutorial isn't a mandatory mod - you just need it if you run into issues (weird things are happening and you've already ruled out the more common suspects) or if the always running fan and illuminated display (even when the printer is turned off) disturbes you. I'm starting with the why part: If you connect a 3D printer via USB to your Raspberry Pi it can lead to all sorts of power related issues. Most of the time those issues occur only if you turn on your pi before …

[Alexander_Kanev]

Hi, @Ewald_Ikemann
I already don't have the SD card in my printer but I just wanted to clarify something. In the post you sent the tape needs to go on the cable that connects the PI to the printer right? Also, will I then have to turn on the printer's power supply for it to work?

[Ewald_Ikemann]

@Alexander_Kanev

Also, will I then have to turn on the printer's power supply for it to work?

You always have to turn on the printer's power supply to make the printer work. With or without that tape.

[Alexander_Kanev]

Welp, this will probably fix things

[Alexander_Kanev]

So far it's going well, the print has started and there aren't any errors. I also no longer have an undervolting message on octoprint.

[Alexander_Kanev]

The solution: I was an idiot and didn't turn on my printer's power which caused the RPI to undervolt