Octoprint-chituboard: software unresponsive to printing a compatible file

What is the problem?

when I press "print" on a compatible file, absolutely nothing happens

What did you already try to solve it?


  • changed the firmware (asked Elegoo to send over an octoprint compatible set, please see my other post)


  • various debugging procedures such as :
  • trying files that I knew would fail (interestingly those have a different outcome, see logs. "_20x20x20.pw0" was a file I knew would fail and you can see in the log that it does throw an error message)
  • printing the target file directly from USB (works perfectly)
  • checking that I can manipulate the z axis from octopi (I can, and it always feels so cool lol)
  • searching for every single suspicious thing online (disk init fail searched, searched the warning about null byte characters, searched about the odd outputs of M110 checkSum error, M21 disk, checked the github, this forum, everywhere!)
  • used chitubox basic and chitubox pro of multiple versions to slice example files and send them over. these files all print fine on the printer when direct printing from usb stick, but do not send over octoprint


  • opened up my USBA <> USBA cable to make sure there are data lines and shielding. all are present. Tape is affixed over the 5V pin.
  • checked the motherboard for observable issues

my guess is it is something about the communication of the file. out of my depth here, but I think because I get so many Disk Init errors, there may be something about how the pi sends / printer receives data that is in disagreement. but I have been working on this for just over a week and haven't come up with an answer! seems like people may be having similar problems as there are some related topics in the issues section of the octoprint-chituboard github that remain unresolved.

Have you tried running in safe mode?

not applicable I think because safe mode would disable the chituboard plugin (right?)

Did running in safe mode solve the problem?


Systeminfo Bundle

You can download this in OctoPrint's System Information dialog ... no bundle, no support!)

octoprint-systeminfo-20220609205253.zip (1.8 MB)

Additional information about your setup

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

sandisk SD card
RPi 4B
Octopi / octoprint 1.8.1 (latest)
mars 3 firmware as linked in my first post
browser is google chrome

octoprint-logs.zip (58.0 KB)

Thank you in advance for your help! :slight_smile: I appreciate it!

There seems to be an error with the plugin itself:

  File "/home/pi/oprint/lib/python3.7/site-packages/flask/app.py", line 1525, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/pi/oprint/lib/python3.7/site-packages/flask/app.py", line 1523, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/pi/oprint/lib/python3.7/site-packages/flask/app.py", line 1509, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**req.view_args)
  File "/home/pi/oprint/lib/python3.7/site-packages/octoprint/server/util/flask.py", line 1508, in decorated_view
    return func(*args, **kwargs)
  File "/home/pi/oprint/lib/python3.7/site-packages/octoprint/server/api/files.py", line 865, in gcodeFileCommand
    printer.select_file(filenameToSelect, sd, printAfterLoading, user)
  File "/home/pi/oprint/lib/python3.7/site-packages/octoprint_chituboard/sla_printer.py", line 130, in select_file
    sliced_model_file = file_format.read(Path(path_on_disk))
  File "/home/pi/oprint/lib/python3.7/site-packages/octoprint_chituboard/file_formats/ctb.py", line 206, in read
    ctb_param = CTBParam.unpack(file.read(CTBParam.get_size()))
  File "/home/pi/oprint/lib/python3.7/site-packages/typedstruct.py", line 89, in unpack
    return cls(*unpack(cls.get_format(), buffer))
struct.error: unpack requires a buffer of 60 bytes

This might be a good one to report as a bug on GitHub:

Also tagging @rudetrooper here in case they have advice as well.

Thank you so much Charlie! I really appreciate it. I will report it as a bug on Github :slight_smile:

Trying to understand what you sent over to make sure I understand... so it is a data type error in the plugin? and that is why it is failing to send the file over?

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