Re: /dev/ttyUSB0 file disappears on Ubuntu 22.04

[Yuri <info@toniclab.ru>]

Thanks for a quick reply, Greg. No, no error here. No matter when I 
execute this on my PC under Ubuntu 22.04

ls -l /dev/ttyUSB*

I get this

ls: cannot access '/dev/ttyUSB*': No such file or directory

I made this log after attaching and removing the device. Here's dmesg 
output

[ 2276.613198] usb 2-1.5: new full-speed USB device number 5 using 
ehci-pci
[ 2276.727502] usb 2-1.5: New USB device found, idVendor=0403, 
idProduct=6001, bcdDevice= 6.00
[ 2276.727511] usb 2-1.5: New USB device strings: Mfr=1, Product=2, 
SerialNumber=3
[ 2276.727514] usb 2-1.5: Product: USB Serial
[ 2276.727516] usb 2-1.5: Manufacturer: FTDI
[ 2276.727518] usb 2-1.5: SerialNumber: FT0KKBIF
[ 2276.729550] ftdi_sio 2-1.5:1.0: FTDI USB Serial Device converter 
detected
[ 2276.729626] usb 2-1.5: Detected FT232RL
[ 2276.730487] usb 2-1.5: FTDI USB Serial Device converter now attached 
to ttyUSB0
[ 3173.152415] usb 2-1.5: USB disconnect, device number 5
[ 3173.152974] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now 
disconnected from ttyUSB0
[ 3173.153005] ftdi_sio 2-1.5:1.0: device disconnected
[ 3182.847132] kauditd_printk_skb: 1 callbacks suppressed
[ 3396.861511] usb 2-1.5: new full-speed USB device number 6 using 
ehci-pci
[ 3396.975858] usb 2-1.5: New USB device found, idVendor=0403, 
idProduct=6001, bcdDevice= 6.00
[ 3396.975866] usb 2-1.5: New USB device strings: Mfr=1, Product=2, 
SerialNumber=3
[ 3396.975870] usb 2-1.5: Product: USB Serial
[ 3396.975872] usb 2-1.5: Manufacturer: FTDI
[ 3396.975874] usb 2-1.5: SerialNumber: FT0KKBIF
[ 3396.978651] ftdi_sio 2-1.5:1.0: FTDI USB Serial Device converter 
detected
[ 3396.978714] usb 2-1.5: Detected FT232RL
[ 3396.979568] usb 2-1.5: FTDI USB Serial Device converter now attached 
to ttyUSB0
[ 3553.309826] usb 2-1.5: USB disconnect, device number 6
[ 3553.310371] ftdi_sio ttyUSB0: FTDI USB Serial Device converter now 
disconnected from ttyUSB0
[ 3553.310404] ftdi_sio 2-1.5:1.0: device disconnected


And here's the syslog output echoing log above

Jun  2 10:41:54 qgs-comp kernel: [ 3173.152415] usb 2-1.5: USB 
disconnect, device number 5
Jun  2 10:41:54 qgs-comp kernel: [ 3173.152974] ftdi_sio ttyUSB0: FTDI 
USB Serial Device converter now disconnected from ttyUSB0
Jun  2 10:41:54 qgs-comp kernel: [ 3173.153005] ftdi_sio 2-1.5:1.0: 
device disconnected
Jun  2 10:42:02 qgs-comp systemd[1786]: Started Application launched by 
gnome-shell.
Jun  2 10:42:03 qgs-comp libreoffice-writer.desktop[7821]: Warning: 
failed to launch javaldx - java may not function correctly
Jun  2 10:42:04 qgs-comp kernel: [ 3182.847132] kauditd_printk_skb: 1 
callbacks suppressed
Jun  2 10:42:04 qgs-comp kernel: [ 3182.847137] audit: type=1400 
audit(1654155724.011:126): apparmor="ALLOWED" operation="file_mmap" 
profile="libreoffice-soffice" name="/tmp/.glQ6PDw2" pid=7839 
comm="soffice.bin" requested_mask="m" denied_mask="m" fsuid=1000 
ouid=1000
Jun  2 10:42:04 qgs-comp kernel: [ 3183.137037] audit: type=1400 
audit(1654155724.303:127): apparmor="ALLOWED" operation="connect" 
profile="libreoffice-soffice" name="/run/user/1000/at-spi/bus_1" 
pid=7838 comm="soffice.bin" requested_mask="wr" denied_mask="wr" 
fsuid=1000 ouid=1000
Jun  2 10:42:04 qgs-comp kernel: [ 3183.137207] audit: type=1400 
audit(1654155724.303:128): apparmor="ALLOWED" operation="file_perm" 
profile="libreoffice-soffice" name="/run/user/1000/at-spi/bus_1" 
pid=7838 comm="soffice.bin" requested_mask="r" denied_mask="r" 
fsuid=1000 ouid=1000
Jun  2 10:42:04 qgs-comp kernel: [ 3183.137218] audit: type=1400 
audit(1654155724.303:129): apparmor="ALLOWED" operation="file_perm" 
profile="libreoffice-soffice" name="/run/user/1000/at-spi/bus_1" 
pid=7838 comm="soffice.bin" requested_mask="r" denied_mask="r" 
fsuid=1000 ouid=1000
Jun  2 10:42:14 qgs-comp systemd[1786]: 
app-gnome-libreoffice\x2dwriter-7821.scope: Consumed 3.025s CPU time.
Jun  2 10:45:38 qgs-comp kernel: [ 3396.861511] usb 2-1.5: new 
full-speed USB device number 6 using ehci-pci
Jun  2 10:45:38 qgs-comp kernel: [ 3396.975858] usb 2-1.5: New USB 
device found, idVendor=0403, idProduct=6001, bcdDevice= 6.00
Jun  2 10:45:38 qgs-comp kernel: [ 3396.975866] usb 2-1.5: New USB 
device strings: Mfr=1, Product=2, SerialNumber=3
Jun  2 10:45:38 qgs-comp kernel: [ 3396.975870] usb 2-1.5: Product: USB 
Serial
Jun  2 10:45:38 qgs-comp kernel: [ 3396.975872] usb 2-1.5: Manufacturer: 
FTDI
Jun  2 10:45:38 qgs-comp kernel: [ 3396.975874] usb 2-1.5: SerialNumber: 
FT0KKBIF
Jun  2 10:45:38 qgs-comp kernel: [ 3396.978651] ftdi_sio 2-1.5:1.0: FTDI 
USB Serial Device converter detected
Jun  2 10:45:38 qgs-comp kernel: [ 3396.978714] usb 2-1.5: Detected 
FT232RL
Jun  2 10:45:38 qgs-comp kernel: [ 3396.979568] usb 2-1.5: FTDI USB 
Serial Device converter now attached to ttyUSB0
Jun  2 10:45:38 qgs-comp mtp-probe: checking bus 2, device 6: 
"/sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5"
Jun  2 10:45:38 qgs-comp mtp-probe: bus: 2, device: 6 was not an MTP 
device
Jun  2 10:45:38 qgs-comp systemd-udevd[7907]: 2-1.5: Failed to 
create/update device symlink '/dev/ttyUSB0', ignoring: File exists
Jun  2 10:45:38 qgs-comp snapd[938]: hotplug.go:199: hotplug device add 
event ignored, enable experimental.hotplug
Jun  2 10:45:38 qgs-comp mtp-probe: checking bus 2, device 6: 
"/sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5"
Jun  2 10:45:38 qgs-comp mtp-probe: bus: 2, device: 6 was not an MTP 
device
Jun  2 10:45:40 qgs-comp ModemManager[1055]: <info>  [base-manager] 
couldn't check support for device 
'/sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.5': not supported by 
any plugin
Jun  2 10:45:47 qgs-comp kernel: [ 3406.230869] [UFW BLOCK] IN=enp5s0 
OUT= MAC=01:00:5e:00:00:01:c4:6e:1f:70:4f:f4:08:00 SRC=192.168.0.1 
DST=224.0.0.1 LEN=32 TOS=0x00 PREC=0xC0 TTL=1 ID=0 DF PROTO=2
Jun  2 10:46:34 qgs-comp systemd[1786]: Started Application launched by 
gnome-shell.
Jun  2 10:46:34 qgs-comp systemd[1786]: Started VTE child process 7940 
launched by gnome-terminal-server process 5736.
Jun  2 10:46:34 qgs-comp gnome-shell[2070]: Can't update stage views 
actor <unnamed>[<MetaWindowGroup>:0x55cea707c320] is on because it needs 
an allocation.
Jun  2 10:46:34 qgs-comp gnome-shell[2070]: Can't update stage views 
actor <unnamed>[<MetaWindowActorX11>:0x55ceb6917ed0] is on because it 
needs an allocation.
Jun  2 10:46:34 qgs-comp gnome-shell[2070]: Can't update stage views 
actor <unnamed>[<MetaSurfaceActorX11>:0x55cea8afc6c0] is on because it 
needs an allocation.
Jun  2 10:46:37 qgs-comp systemd[1786]: Started Application launched by 
gnome-shell.
Jun  2 10:46:37 qgs-comp systemd[1786]: Started VTE child process 7958 
launched by gnome-terminal-server process 5736.
Jun  2 10:46:37 qgs-comp gnome-shell[2070]: Can't update stage views 
actor <unnamed>[<MetaWindowGroup>:0x55cea707c320] is on because it needs 
an allocation.
Jun  2 10:46:37 qgs-comp gnome-shell[2070]: Can't update stage views 
actor <unnamed>[<MetaWindowActorX11>:0x55cea8e32360] is on because it 
needs an allocation.
Jun  2 10:46:37 qgs-comp gnome-shell[2070]: Can't update stage views 
actor <unnamed>[<MetaSurfaceActorX11>:0x55cea8afca40] is on because it 
needs an allocation.
Jun  2 10:48:14 qgs-comp kernel: [ 3553.309826] usb 2-1.5: USB 
disconnect, device number 6
Jun  2 10:48:14 qgs-comp kernel: [ 3553.310371] ftdi_sio ttyUSB0: FTDI 
USB Serial Device converter now disconnected from ttyUSB0
Jun  2 10:48:14 qgs-comp kernel: [ 3553.310404] ftdi_sio 2-1.5:1.0: 
device disconnected


No problems on the same PC working under Ubuntu 18.04 and 16.04 
whatsoever:

ls -l /dev/ttyUSB*
crw-rw---- 1 root dialout 188, 0 Jun  2 10:36 /dev/ttyUSB0


> 
> I do not see it going away.
> 
> Are you sure it is gone?  Any further log messages?
> 
> thanks,
> 
> greg k-h