I have been using Inkscape to cut with my Liyu SC631 cutter using 18.04 for a number of years.  I have now got a new dual boot PC running Windows 11 and Ubuntu 24.04.  Thanks to help on the forum I have now got the cutter working with Windows 11, but I still can't get it to work with Ubuntu 24,04, which is my preferred operating system.  Can anyone help with this please?

Inkscape opens fine in 24.04, but when I try to cut I get the message "Could not open serial port. Please check your device is running, connected and the settings are correct".

I can't run Inkscape using sudo as when I try that I get a message "mkdir: cannot create directory '/run/user/0@: Permission denied Authorization required, but no authorization protocal specified". Sudo works fine on my old machine. Is this possibly because Inkscape is installed as a snap on the new machine, as recommended by Canonical?

I am using the same settings as work on my 18.04 machine, which are the same for Windows 11 except that under Windows I use serial port COM4 and on the Ubuntu systems I am using /dev/ttyUSB0.  On both my old and new machines dmesg finds ttyUSB0 after I plug the cutter into a USB port.

I am in the group dialout on both the old and new machines.

It might be some sort of permissions problem, but many hours of internet searching have yet to yield anything helpful.

I would welcome any help with this.

I have finally sorted the issue.  I had Inkscape installed as a snap on my Ubuntu 24.04 machine.  After uninstalling the snap and installing Inkscape using apt the plotter worked.  Conclusion - there is a problem with the snap version which interferes with the proper operation of Export/Plot.

The problem seems to be that the Inkscape snap has confinement set to strict.  As is explained here https://snapcraft.io/docs/snap-confinement this can limit an apps access to system resources.  The problem is that unless you are aware of the limitations of snaps with strict confinement, and I wasn't, there is nothing in the current description of the Inkscape snap or in the way menus are presented (by, for example, greying out options) to warn you that snap won't work properly.