Re: /dev/ttyUSB0 file disappears on Ubuntu 22.04

Yuri
2022-06-02T08:48:00Z

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