Cancel on LCD not Cancelling OctoPrint

Hi all!

Just recently upgraded to 4.0.6 from 3.0.2, and I’m really liking the changes! I do have a troubling bug that I need to squash, though. If I hit the cancel button on the LCD, the machine goes through its normal cancel routine of increasing the Z distance then homing the y axis. Unfortunately, OctoPrint doesn’t get the memo and continues to send gcode to the printer. This results in the the printer kicking back into gear and start printing where it left off. I think the problem statement is simple: OctoPrint is not receiving a cancel message, but I’m not sure why not. Any help? Thanks!


This is a very tricky subject. There is in fact no way to cancel a job from the printer itself. If you look at the document:

you see only pause, resume, disconnect. This is not the fault of OctoPrint. This is the fault of Gcode and its very partial, incomplete, confusing, … definition.

I tried many different solutions but none is satisfying.

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Interesting! With 3.0.2, I think cancel would send a disconnect signal. Is there a way to regain that behavior? Is there a reason I shouldn’t be cancelling a job from the printer to force a disconnect from Octoprint? Thanks again for all you do!

Yes, it does. But it is not very user-friendly as you have to reconnect the printer to do another print.

Fo version 5, I will re-evaluate this and perhaps talks with Gina (creator of OctoPrint) to find a proper solution.

Using 4.0.6, printing from an SD card.
The printer continues to warm up if I stop/cancel a job before it begins. v3.0.2 would stop functions immediately. I haven’t waited to see what happens when it reaches temperature; just cut the power and reboot. This is from the onboard card slot, not Octoprint. Is this related?

Wanhao Duplicator i3 Plus, 2016 model

Frankly, I do not remember how this was implemented in version 3. Was a long time ago.

Tbh if hitting cancel on octo doesn’t work (happens sometimes) I just pull the usb cable. Messy, but works if you have a catastrophic fail. Does the same thing, with the same complications (have to reconnect).