Now it is
Bus 001 Device 005: ID 1a86:7523 QinHeng Electronics HL-340 USB-Serial adapter crw-rw-r--+ 1 root root 189, 4 Nov 18 23:49 /dev/bus/usb/001/005 getfacl !$ getfacl /dev/bus/usb/001/005 getfacl: Removing leading '/' from absolute path names # file: dev/bus/usb/001/005 # owner: root # group: root user::rw- user:hadmut:rw- group::rw- mask::rw- other::r-- crw-rw----+ 1 root dialout 188, 0 Nov 18 23:54 /dev/ttyUSB0 getfacl /dev/ttyUSB0 getfacl: Removing leading '/' from absolute path names # file: dev/ttyUSB0 # owner: root # group: dialout user::rw- user:hadmut:rw- group::rw- mask::rw- other::--- Thanks for the strace hint. After solving the apparmor problem and with strace I found that the problem may now be something different. cura can open and write to the printer and does. But it tries different baud rates in order to detect the appropriate one, and maybe confuses the Printer this way. And it doesn't always detect the correct baud rate. Sending data with the wrong baud rate can result in random nonsense data being sent, and maybe the printer just can't cope with that. However: Your hints helped me a lot (thanks) and brought my steps forward. One major question: Can the changes in apparmor be achieved by the snap maintainer, or do I have to do them manually after snap installation? regards -- 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
