You can collect a strace of the app by running: snap run --strace='-vf -s 256' cura-slicer.cura
And yes, as @alexmurray indicated, this may be something with device cgroups. The problem with those is there is nothing logged if access is denied, making the debugging process complicated. Assuming that you have not unplugged the printer, and it's still the same USB device inside the kernel, IOW this device: > Bus 001 Device 003: ID 1a86:7523 QinHeng Electronics HL-340 USB-Serial adapter Can you do `ls -l /dev/bus/usb/001/003` and attach the output? It should look like this: crw-rw-r-- 1 root root 189, 2 11-17 07:36 /dev/bus/usb/001/003 The column right next to root:root is the major and minor numbers of this device. Having this, please check whether /sys/fs/cgroup/devices/snap.cura-slicer.cura/devices.list contains an entry 'c 189:2'. Next, you can run `udevadm info /dev/bus/usb/001/003` and attach the output. However, since it's a USB serial device, I suspect that the actual communication happens over one of the /dev/ttyUSB* devices. Please check whether any /dev/ttyUSB* devices exist and attach the output of `udevadm info /dev/ttyUSB*`. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1950855 Title: Can't enable snap to print on a usb printer To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/snapd/+bug/1950855/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
