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lost connection #227

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lost connection#227

Description

@simontheflutist
simontheflutist
opened on Aug 8, 2026

followed instructions on flash.comma.ai

port 1 cable is my Comma 3X's OBD-C.

Bug Report - flash.comma.ai

Device: comma four
Serial: N/A
Error: LOST_CONNECTION
Step: CONNECTING
Last Message: N/A

OS: Linux
Sandbox: None detected
Browser: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/151.0.0.0 Safari/537.36
URL: https://flash.comma.ai/
Time: 2026-08-08T00:24:01.285Z

Console Logs 
[2026-08-08T00:23:45.605Z] [info] flash.comma.ai version: 2a2da7f
[2026-08-08T00:23:45.947Z] [info] [ImageManager] Initialized
[2026-08-08T00:23:55.238Z] [error] [Flash] Connection error {}
[2026-08-08T00:23:55.240Z] [debug] [Flash] error 4

Activity

  1. simontheflutist commented on Aug 8, 2026

    @simontheflutist
    simontheflutist
    on Aug 8, 2026
    Author

    error when using my Apple USB-C

    Bug Report - flash.comma.ai

    Device: comma four
    Serial: N/A
    Error: LOST_CONNECTION
    Step: CONNECTING
    Last Message: N/A

    OS: Linux
    Sandbox: None detected
    Browser: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/151.0.0.0 Safari/537.36
    URL: https://flash.comma.ai/
    Time: 2026-08-08T00:28:38.434Z

    Console Logs 
    [2026-08-08T00:28:23.856Z] [info] flash.comma.ai version: 2a2da7f
[2026-08-08T00:28:23.903Z] [info] [ImageManager] Initialized
[2026-08-08T00:28:36.371Z] [error] [Flash] Connection error {}
[2026-08-08T00:28:36.373Z] [debug] [Flash] error 4

  2. simontheflutist commented on Aug 8, 2026

    @simontheflutist
    simontheflutist
    on Aug 8, 2026
    Author

    power from car harness, data from laptop

    Bug Report - flash.comma.ai

    Device: comma four
    Serial: N/A
    Error: LOST_CONNECTION
    Step: CONNECTING
    Last Message: N/A

    OS: Linux
    Sandbox: None detected
    Browser: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/151.0.0.0 Safari/537.36
    URL: https://flash.comma.ai/
    Time: 2026-08-08T00:39:04.991Z

    Console Logs 
    [2026-08-08T00:38:48.405Z] [info] flash.comma.ai version: 2a2da7f
[2026-08-08T00:38:49.272Z] [info] [ImageManager] Initialized
[2026-08-08T00:38:58.233Z] [error] [Flash] Connection error {}
[2026-08-08T00:38:58.235Z] [debug] [Flash] error 4

  3. simontheflutist commented on Aug 8, 2026

    @simontheflutist
    simontheflutist
    on Aug 8, 2026
    Author

    On my Android phone, USB-C to data port simply doesn't work. The device just boots normally and doesn't show up in flash.comma.ai.

  4. simontheflutist commented on Aug 8, 2026

    @simontheflutist
    simontheflutist
    on Aug 8, 2026
    Author

    What I've tried: two different USB-C cables, my 3X's OBD-C and an Apple USB-C. Laptop (Chrome/Ubuntu) and S26 phone (Chrome/Android). Power from 5V Dell charger and from 12V car harness.

  5. simontheflutist commented on Aug 8, 2026

    @simontheflutist
    simontheflutist
    on Aug 8, 2026
    Author

    Tried a third USB cable of unknown provenance. Same error. Chrome with and without incognito mode.

  6. simontheflutist commented on Aug 8, 2026

    @simontheflutist
    simontheflutist
    on Aug 8, 2026
    Author

    Same error on a fourth USB cable. Support ticket 82804.

  7. stefpi commented on Aug 8, 2026

    @stefpi
    stefpi
    on Aug 8, 2026

    work around for now

    start a chrome instance with a fresh user data directory:

    google-chrome --user-data-dir=/tmp/flash-chrome-test https://flash.comma.ai

    and then run the flash process as normal

  8. stefpi commented on Aug 8, 2026

    @stefpi
    stefpi
    on Aug 8, 2026

    another good place to look when stuff like this happens is: chrome://device-log/

    for example. I was also having connection issues and the following was in my device log:
    Image

    this is a bad experience though, so we need to figure out why this happens in the first place

  9. adeebshihadeh commented on Aug 8, 2026

    @adeebshihadeh
    adeebshihadeh
    on Aug 8, 2026
    Collaborator

    Looks like a permission issue?

  10. stefpi commented on Aug 8, 2026

    @stefpi
    stefpi
    on Aug 8, 2026

    my chromium was installed from the ubuntu app center via snap which requires a connection to raw-usb snap package in order for flash to work.

    in comparison, my google chrome installed via .deb from google website runs outside of sandbox and doesn't need anything.

    Image

  11. simontheflutist commented on Aug 8, 2026

    @simontheflutist
    simontheflutist
    on Aug 8, 2026
    Author

    my Google Chrome is installed via deb too. Before trying your workaround @stefpi this is the error I get in device-log:

    Image

  12. simontheflutist commented on Aug 8, 2026

    @simontheflutist
    simontheflutist
    on Aug 8, 2026
    Author

    @stefpi even with your user-dir workaround, I get the same error.

    Image

    Bug Report - flash.comma.ai

    Device: comma four
    Serial: N/A
    Error: LOST_CONNECTION
    Step: CONNECTING
    Last Message: N/A

    OS: Linux
    Sandbox: None detected
    Browser: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/151.0.0.0 Safari/537.36
    URL: https://flash.comma.ai/
    Time: 2026-08-08T02:28:09.761Z

    Console Logs 
    [2026-08-08T02:27:56.225Z] [info] flash.comma.ai version: 2a2da7f
[2026-08-08T02:27:57.560Z] [info] [ImageManager] Initialized
[2026-08-08T02:28:03.894Z] [error] [Flash] Connection error {}
[2026-08-08T02:28:03.895Z] [debug] [Flash] error 4

  13. andiradulescu commented on Aug 8, 2026

    @andiradulescu
    andiradulescu
    on Aug 8, 2026
    Collaborator

    permission error for #227 (comment) reported in #110

    might be a good time to put a PR to detect this case and show the user the command it needs to run

  14. simontheflutist commented on Aug 8, 2026

    @simontheflutist
    simontheflutist
    on Aug 8, 2026
    Author

    @andiradulescu that report is for snap install chromium. I'm on Google's deb:

    (base) simon@simon-Precision-5560:~$ sudo apt show google-chrome-stable
Package: google-chrome-stable
Version: 151.0.7922.108-1
Priority: optional
Section: web
Maintainer: Chrome Linux Team <chromium-dev@chromium.org>
Installed-Size: 452 MB
Provides: www-browser
Pre-Depends: dpkg (>= 1.14.0)
Depends: ca-certificates, fonts-liberation, libasound2 (>= 1.0.17), libatk-bridge2.0-0 (>= 2.5.3), libatk1.0-0 (>= 2.11.90), libatspi2.0-0 (>= 2.9.90), libc6 (>= 2.25), libcairo2 (>= 1.6.0), libcups2 (>= 1.6.0), libcurl3-gnutls | libcurl3-nss | libcurl4 | libcur>
Download-Size: 140 MB
APT-Manual-Installed: yes
APT-Sources: https://dl.google.com/linux/chrome-stable/deb stable/main amd64 Packages
Description: The web browser from Google
 Google Chrome is a browser that combines a minimal design with sophisticated technology to make the web faster, safer, and easier.

  15. andiradulescu commented on Aug 8, 2026

    @andiradulescu
    andiradulescu
    on Aug 8, 2026
    Collaborator

    @simontheflutist yes, I read, I forgot to quote #227 (comment)

  16. andiradulescu commented on Aug 8, 2026

    @andiradulescu
    andiradulescu
    on Aug 8, 2026
    Collaborator

    @simontheflutist I know it might sound stupid, but did you try to run the snap command, though?

    sudo snap connect chromium:raw-usb

    actually nevermind, impossible to be this

  17. andiradulescu commented on Aug 8, 2026

    @andiradulescu
    andiradulescu
    on Aug 8, 2026
    Collaborator

    Could you run these while the comma four is connected, ideally also while attempting the connection in flash.comma.ai?

    lsusb
udevadm monitor --kernel --udev --property

    Then:

    ls -l /dev/bus/usb/BBB/DDD
getfacl /dev/bus/usb/BBB/DDD
udevadm info --query=all --name=/dev/bus/usb/BBB/DDD

    Where BBB/DDD are the ones you see in the chrome logs.

  18. cwiggs commented on Sep 6, 2026

    @cwiggs
    cwiggs
    on Sep 6, 2026

    I'm getting the same error on my Debian testing laptop with a Comma 4.

    lsusb:

     ╚═ $ lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 003 Device 003: ID 27c6:609c Shenzhen Goodix Technology Co.,Ltd. Goodix Fingerprint USB Device
Bus 003 Device 004: ID 8087:0032 Intel Corp. AX210 Bluetooth
Bus 003 Device 013: ID 1050:0406 Yubico.com Yubikey 4/5 U2F+CCID
Bus 003 Device 091: ID 3801:9008 Qualcomm CDMA Technologies MSM QUSB_BULK_CID:0402_SN:5105F421
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub

    I believe Bus 003 Device 091: ID 3801:9008 Qualcomm CDMA Technologies MSM QUSB_BULK_CID:0402_SN:5105F421 is the Comma 4.

    Some udev results:

    UDEV  [953539.464566] add      /devices/pci0000:00/0000:00:14.0/usb3/3-3 (usb)
ACTION=add
DEVPATH=/devices/pci0000:00/0000:00:14.0/usb3/3-3
SUBSYSTEM=usb
DEVNAME=/dev/bus/usb/003/092
DEVTYPE=usb_device
PRODUCT=3801/9008/0
TYPE=0/0/0
BUSNUM=003
DEVNUM=092
SEQNUM=39200
DRIVER=usb
USEC_INITIALIZED=953539447128
ID_BUS=usb
ID_MODEL=QUSB_BULK_CID:0402_SN:5105F421
ID_MODEL_ENC=QUSB_BULK_CID:0402_SN:5105F421
ID_MODEL_ID=9008
ID_SERIAL=Qualcomm_CDMA_Technologies_MSM_QUSB_BULK_CID:0402_SN:5105F421
ID_VENDOR=Qualcomm_CDMA_Technologies_MSM
ID_VENDOR_ENC=Qualcomm\x20CDMA\x20Technologies\x20MSM
ID_VENDOR_ID=3801
ID_REVISION=0000
ID_USB_MODEL=QUSB_BULK_CID:0402_SN:5105F421
ID_USB_MODEL_ENC=QUSB_BULK_CID:0402_SN:5105F421
ID_USB_MODEL_ID=9008
ID_USB_SERIAL=Qualcomm_CDMA_Technologies_MSM_QUSB_BULK_CID:0402_SN:5105F421
ID_USB_VENDOR=Qualcomm_CDMA_Technologies_MSM
ID_USB_VENDOR_ENC=Qualcomm\x20CDMA\x20Technologies\x20MSM
ID_USB_VENDOR_ID=3801
ID_USB_REVISION=0000
ID_USB_INTERFACES=:ffff10:
ID_PATH_WITH_USB_REVISION=pci-0000:00:14.0-usbv2-0:3
ID_PATH=pci-0000:00:14.0-usb-0:3
ID_PATH_TAG=pci-0000_00_14_0-usb-0_3
ID_INTEGRATION=external
ID_FOR_SEAT=usb-pci-0000_00_14_0-usb-0_3
MAJOR=189
MINOR=347
TAGS=:seat:
CURRENT_TAGS=:seat:

UDEV  [953539.469118] change   /devices/pci0000:00/0000:00:14.0/usb3/3-3 (usb)
ACTION=change
DEVPATH=/devices/pci0000:00/0000:00:14.0/usb3/3-3
SUBSYSTEM=usb
DEVNAME=/dev/bus/usb/003/092
DEVTYPE=usb_device
DRIVER=usb
PRODUCT=3801/9008/0
TYPE=0/0/0
BUSNUM=003
DEVNUM=092
SEQNUM=39201
USEC_INITIALIZED=953539447128
ID_BUS=usb
ID_MODEL=QUSB_BULK_CID:0402_SN:5105F421
ID_MODEL_ENC=QUSB_BULK_CID:0402_SN:5105F421
ID_MODEL_ID=9008
ID_SERIAL=Qualcomm_CDMA_Technologies_MSM_QUSB_BULK_CID:0402_SN:5105F421
ID_VENDOR=Qualcomm_CDMA_Technologies_MSM
ID_VENDOR_ENC=Qualcomm\x20CDMA\x20Technologies\x20MSM
ID_VENDOR_ID=3801
ID_REVISION=0000
ID_USB_MODEL=QUSB_BULK_CID:0402_SN:5105F421
ID_USB_MODEL_ENC=QUSB_BULK_CID:0402_SN:5105F421
ID_USB_MODEL_ID=9008
ID_USB_SERIAL=Qualcomm_CDMA_Technologies_MSM_QUSB_BULK_CID:0402_SN:5105F421
ID_USB_VENDOR=Qualcomm_CDMA_Technologies_MSM
ID_USB_VENDOR_ENC=Qualcomm\x20CDMA\x20Technologies\x20MSM
ID_USB_VENDOR_ID=3801
ID_USB_REVISION=0000
ID_USB_INTERFACES=:ffff10:
ID_PATH_WITH_USB_REVISION=pci-0000:00:14.0-usbv2-0:3
ID_PATH=pci-0000:00:14.0-usb-0:3
ID_PATH_TAG=pci-0000_00_14_0-usb-0_3
ID_INTEGRATION=external
ID_FOR_SEAT=usb-pci-0000_00_14_0-usb-0_3
MAJOR=189
MINOR=347
TAGS=:seat:
CURRENT_TAGS=:seat:

UDEV  [953539.473447] add      /devices/pci0000:00/0000:00:14.0/usb3/3-3/3-3:1.0 (usb)                   20:49 [10/3628]
ACTION=add                  
DEVPATH=/devices/pci0000:00/0000:00:14.0/usb3/3-3/3-3:1.0   
SUBSYSTEM=usb                                                                                                           
DEVTYPE=usb_interface
PRODUCT=3801/9008/0                                         
TYPE=0/0/0                                                                                                              
INTERFACE=255/255/16        
MODALIAS=usb:v3801p9008d0000dc00dsc00dp00icFFiscFFip10in00  
SEQNUM=39202       
USEC_INITIALIZED=953539454928
ID_PATH_WITH_USB_REVISION=pci-0000:00:14.0-usbv2-0:3:1.0    
ID_PATH=pci-0000:00:14.0-usb-0:3:1.0                                                                                    
ID_PATH_TAG=pci-0000_00_14_0-usb-0_3_1_0 

UDEV  [953539.482106] bind     /devices/pci0000:00/0000:00:14.0/usb3/3-3 (usb)                                          
ACTION=bind                 
DEVPATH=/devices/pci0000:00/0000:00:14.0/usb3/3-3           
SUBSYSTEM=usb                                                                                                           
DEVNAME=/dev/bus/usb/003/092
DEVTYPE=usb_device                                          
DRIVER=usb                                                  
PRODUCT=3801/9008/0         
TYPE=0/0/0                                                                                                              
BUSNUM=003                                                  
DEVNUM=092                                                  
SEQNUM=39203                                                
USEC_INITIALIZED=953539447128                               
ID_BUS=usb                                                  
ID_MODEL=QUSB_BULK_CID:0402_SN:5105F421                                                                                 
ID_MODEL_ENC=QUSB_BULK_CID:0402_SN:5105F421                 
ID_MODEL_ID=9008                                                                                                        
ID_SERIAL=Qualcomm_CDMA_Technologies_MSM_QUSB_BULK_CID:0402_SN:5105F421                                                 
ID_VENDOR=Qualcomm_CDMA_Technologies_MSM                                                                                
ID_VENDOR_ENC=Qualcomm\x20CDMA\x20Technologies\x20MSM       
ID_VENDOR_ID=3801                                           
ID_REVISION=0000          
ID_USB_MODEL=QUSB_BULK_CID:0402_SN:5105F421                                                                             
ID_USB_MODEL_ENC=QUSB_BULK_CID:0402_SN:5105F421             
ID_USB_MODEL_ID=9008                                        
ID_USB_SERIAL=Qualcomm_CDMA_Technologies_MSM_QUSB_BULK_CID:0402_SN:5105F421                                             
ID_USB_VENDOR=Qualcomm_CDMA_Technologies_MSM                
ID_USB_VENDOR_ENC=Qualcomm\x20CDMA\x20Technologies\x20MSM   
ID_USB_VENDOR_ID=3801
ID_USB_REVISION=0000
ID_USB_INTERFACES=:ffff10:
ID_PATH_WITH_USB_REVISION=pci-0000:00:14.0-usbv2-0:3
ID_PATH=pci-0000:00:14.0-usb-0:3
ID_PATH_TAG=pci-0000_00_14_0-usb-0_3
ID_INTEGRATION=external
ID_FOR_SEAT=usb-pci-0000_00_14_0-usb-0_3
MAJOR=189
MINOR=347
TAGS=:seat:
CURRENT_TAGS=:seat:

    $ ls  -l /dev/bus/usb/003/092 
crw-rw-r-- 1 root root 189, 347 Sep  5 20:49 /dev/bus/usb/003/092

$ getfacl /dev/bus/usb/003/092 
getfacl: Removing leading '/' from absolute path names
# file: dev/bus/usb/003/092
# owner: root
# group: root
user::rw-
group::rw-
other::r--

    output of udevadm info --query=all --name=/dev/bus/usb/003/092 

    M: 3-3
R: 3
J: c189:347
U: usb
T: usb_device
D: c 189:347
N: bus/usb/003/092
L: 0
V: usb
E: DEVPATH=/devices/pci0000:00/0000:00:14.0/usb3/3-3
E: DEVNAME=/dev/bus/usb/003/092
E: DEVTYPE=usb_device
E: DRIVER=usb
E: PRODUCT=3801/9008/0
E: TYPE=0/0/0
E: BUSNUM=003
E: DEVNUM=092
E: MAJOR=189
E: MINOR=347
E: SUBSYSTEM=usb
E: USEC_INITIALIZED=953539447128
E: ID_BUS=usb
E: ID_MODEL=QUSB_BULK_CID:0402_SN:5105F421
E: ID_MODEL_ENC=QUSB_BULK_CID:0402_SN:5105F421
E: ID_MODEL_ID=9008
E: ID_SERIAL=Qualcomm_CDMA_Technologies_MSM_QUSB_BULK_CID:0402_SN:5105F421
E: ID_VENDOR=Qualcomm_CDMA_Technologies_MSM
E: ID_VENDOR_ENC=Qualcomm\x20CDMA\x20Technologies\x20MSM
E: ID_VENDOR_ID=3801
E: ID_REVISION=0000
E: ID_USB_MODEL=QUSB_BULK_CID:0402_SN:5105F421
E: ID_USB_MODEL_ENC=QUSB_BULK_CID:0402_SN:5105F421
E: ID_USB_MODEL_ID=9008
E: ID_USB_SERIAL=Qualcomm_CDMA_Technologies_MSM_QUSB_BULK_CID:0402_SN:5105F421
E: ID_USB_VENDOR=Qualcomm_CDMA_Technologies_MSM
E: ID_USB_VENDOR_ENC=Qualcomm\x20CDMA\x20Technologies\x20MSM
E: ID_USB_VENDOR_ID=3801
E: ID_USB_REVISION=0000
E: ID_USB_INTERFACES=:ffff10:
E: ID_PATH_WITH_USB_REVISION=pci-0000:00:14.0-usbv2-0:3
E: ID_PATH=pci-0000:00:14.0-usb-0:3
E: ID_PATH_TAG=pci-0000_00_14_0-usb-0_3
E: ID_INTEGRATION=external
E: ID_FOR_SEAT=usb-pci-0000_00_14_0-usb-0_3
E: TAGS=:seat:
E: CURRENT_TAGS=:seat:```

Hope that helps.

  19. cwiggs commented on Sep 6, 2026

    @cwiggs
    cwiggs
    on Sep 6, 2026

    I had chromium via flatpak installed. I ran flatpak override --user --filesystem=/run/udev:ro org.chromium.Chromium but that did not fix it.

    I also switched to a .deb version and have the same error.

  20. cwiggs commented on Sep 6, 2026

    @cwiggs
    cwiggs
    on Sep 6, 2026

    I also tried:

    1. A different computer, this one running NixOS 26.05.
    2. A different USB cable from computer to Comma 4.

    Both resulted in the same error.

  21. devzeebo commented on Sep 18, 2026

    @devzeebo
    devzeebo
    on Sep 18, 2026

    I had a similar issue. I had AI debug my system and it uncovered 2 things:

    1. The WebUSB can enumerate the device, but was missing user write permission which resulted in the LOST_CONNECTION

    Solved via udev rule. Note: this is the script I had it run. I have a 3X, so I'm not sure where it got the 4 vendor id from. Your mileage may vary

    sudo tee /etc/udev/rules.d/99-comma-qdl.rules <<'EOF'
# comma 3/3X QDL
SUBSYSTEM=="usb", ATTR{idVendor}=="05c6", ATTR{idProduct}=="9008", MODE="0666", TAG+="uaccess"
# comma four QDL (harmless to include)
SUBSYSTEM=="usb", ATTR{idVendor}=="3801", ATTR{idProduct}=="9008", MODE="0666", TAG+="uaccess"
EOF

sudo udevadm control --reload-rules
sudo udevadm trigger

    Then, unplugging and plugging back in via the same 1/2 order that the site describes.

    1. After solving that, the flash started but failed at ~33% of the download. This was related to attempting to do the flash in an Incognito chromium window.

    chromium --user-data-dir="/tmp/comma-flash-chrome" https://flash.comma.ai/

    I'm running Arch and installed chromium via pacman

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