I just did a fresh install of Ubuntu 22.04 and it broke support for CH340 USB to serial adapter based devices. (support was native in 20.04)
When I do /$ ls /dev there is no ttyUSB0 entry in the list.
If I do /$ lsusb I do get : Bus 003 Device 002: ID 1a86:7523 QinHeng Electronics CH340 serial converter

If I do /$ lsmod I can see the right module is loaded : ch34x 24576 0

I tried to manually create the node with mknod /dev/ttyUSB0 c 188 0 and chmod it to 777 but it doesn't work either.

Any help is welcome :)

  • 1
    After plugging in the USB thing, run sudo dmesg the last few lines should show tow the USB device has been identified, and what device names that has been allocated.
    – Soren A
    Apr 22 at 9:46

2 Answers 2


This happens because of conflict between product IDs (a Braille screen reader and my CH340 based chip). Here is the solution :

  1. Edit /usr/lib/udev/rules.d/85-brltty.rules
  2. Search for this line and comment it out:
    ENV{PRODUCT}=="1a86/7523/*", ENV{BRLTTY_BRAILLE_DRIVER}="bm", GOTO="brltty_usb_run"
  3. reboot

More on https://unix.stackexchange.com/questions/670636/unable-to-use-usb-dongle-based-on-usb-serial-converter-chip

  • Editing /usr/lib/udev/rules.d/85-brltty.rules worked for me on PopOS 22.04 to work with a esp8266, but to be sure this is fixed for good I also run sudo apt remove brltty . Thanks :) Sep 10 at 21:32

Unless you are using a braille display this should do the trick:

sudo apt remove brltty 

Don't forget to plug your dongle off and on.

  • 1
    Very helpful I did not expect to find such an obscure reason for my ESP32 not working!
    – Besi
    Sep 14 at 13:34
  • This is just ridiculous. I spent 3 hours trying to figure out why freshly installed Ubuntu with seemingly proper drivers is not accepting my ESP32 with the same wire I used with Raspberry Pi. Thanks! yesterday

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