OctoPrint on linux laptop says "usb0 is busy or does not exist"

What is the problem?

I'm going crazy trying to get this to work. I've installed OctoPrint on an old laptop running Ubuntu and gotten the webcam and everything else working but my Ender 3 will not connect no matter what. The laptop is providing enough power over USB to run the printer off of and the /dev/ttyUSB0 appears in the serial port list as an option. Port /dev/ttyUSB0 also appears when I list /dev/tty* and then disappears when i unplug it as expected.

Im really confused as its providing power and the I believe the detection of USB0 tells me it can transfer data. I've tried all available baudrates. And the error that keeps showing up in the OctoPrint terminal is "usb0 is busy or does not exist". Nothing to my knowledge is using it and I've removed brltty from my install to be sure, and it absolutely does exist.

What did you already try to solve it?

Change cables, power cycle the printer, power cycle the laptop, reinstalled octoprint, reinstalled Ubuntu, different Baudrates, removed brltty, Confirmed the usb is detected.

Systeminfo Bundle

octoprint-systeminfo-20231129141505.zip (19.5 KB)

Additional information about your setup

OctoPrint Version - 1.9.3
Device - Laptop
OS - Ubuntu Latest
Printer - Ender 3

Let's try a solution for a problem that often occurs on Ubuntu:

Run this in the terminal and reboot the machine afterwards sudo apt -y remove brltty.
It removes the brltty package which claims the usb connection when it's running (and installed).

I used sudo apt autoremove brltty already which, I believe, accomplishes the same thing. Didn't fix anything unfortunately.

Run dmesg -w which gives you a constant dmesg output
Disconnect and reconnect the USB cable to the printer.
If you get an output when you reconnect it post it here - if not try another cable until you get an output

[21167.616417] usb 1-1: new full-speed USB device nunber 10 using xhci_hcd
[21167.765518] usb 1-1: New USB device found, idVendor=1a86, idProduct=7523, bcdDevice= 2.64
[21167.765531] usb 1-1: New USB device strings: Mfr=0, Product=2, SerialNunber=0
[21167.765537] usb 1-1: Product: USB Serial
[21167.767648] ch341 1-1:1.0: ch341-uart converter detected
[21167.768217] usb 1-1: ch341-uart converter now attached to ttyUSB0

(I believe this bit below is separate but am including it just in case)

[21168.008257] pcieport 0000:00:1c.5: AER: Corrected error received: 0000:00:1c.5
[21168.008266] pcieport 0000:00:1c.5: PCIe Bus Error: severity=Corrected, typesPhysical Layer, (Receiver ID)
[21168.008268] pcieport 0000:00:1c.5: device [8086:a115] error status/nask=00000001/00002000
[21168.008271] pcieport 0000:00:1c.5: [ 0] RxErr (First)

Do you get that pcie error every time when you plug the printer in?

It goes off frequently but it does not seem to correlate to when I plug in or unplug the USB. It also continues happening every once and a while no matter if the USB is plugged in or not. Seems unrelated to me.

Hm hard to tell what's using the usb port.
Do you have by any chance a slicer like cura running?

Nope, fresh install of ubuntu nothing other than octoprint installed. I gave up witb the laptop and purchased a y split adapter for octo4a to use with an old phone.

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You said the printer is being powered from the USB port. The printer needs to be powered on from its power source. The USB port will NOT Provide enough to run the printer, and if it's not powered on with it's power supply, that could be the source of the problem. Also sudo Auto remove xxx will only remove packages that do not have anything using them. To remove the brltty' you need to use sudap apt remove or sudo apt purge to properly remove it

I had the main power on too, was just explaining that the cable was sending power and data and was using that as an example of power transfer.
I had read elsewhere that 'sudo apt autoremove brltty' would work for that issue, could've been bad information but i did watch as the terminal went through and removed files so unsure.
Either way I just ended up buying a USB C splitter for power and data to use octo4a on an old phone and that works as expected, much less of a headache lol.

Sending power from the Pi/laptop to the printer is never good:

This may be the reason you printer does not connect.
Creality printers are prone to this issue.

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