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Fixing Fractal Adjust Pro Hub LED Control on Ubuntu via WebHID

Recently, I encountered an issue where my Fractal Adjust Pro Hub could not be controlled through the official web interface (adjust.fractal-design.com) on Ubuntu.
Although the device appeared in the connection popup, clicking Connect failed to establish a working link.

After some debugging, I found that the root cause was insufficient permissions to access the USB HID device from the browser.
Here's the full breakdown of the problem and solution.

Problem Symptoms​

  • Device shows up as "Paired" in the WebHID connection dialog but cannot actually connect.
  • Occurs in Ubuntu (and other Linux distros) due to restrictive default permissions on /dev/hidraw* devices.
  • WebHID API in Chrome/Chromium requires the browser to have permission to read/write HID devices.

Step 1 – Identify the Device​

First, connect your Fractal Adjust Pro Hub and run:

lsusb

You should see an entry like:

Bus 003 Device 004: ID 36bc:1001 Fractal Adjust Pro Hub

Here:

  • Vendor ID (VID) = 36bc
  • Product ID (PID) = 1001

Step 2 – Create a udev Rule for Permissions​

By default, only root can access /dev/hidraw*.
We need to grant access to users in the plugdev group.

Run:

# 1) Create the udev rule
echo 'SUBSYSTEM=="hidraw", ATTRS{idVendor}=="36bc", ATTRS{idProduct}=="1001", GROUP="plugdev", MODE="0660"' | sudo tee /etc/udev/rules.d/99-fractal-adjust-pro.rules

# 2) Add your user to plugdev group
sudo usermod -aG plugdev "$USER"

# 3) Reload rules and re-trigger udev
sudo udevadm control --reload-rules
sudo udevadm trigger

Step 3 – Reconnect the Device​

  1. Log out and log back in (or reboot) to apply the group change.
  2. Unplug and re-plug the Fractal Adjust Pro Hub.
  3. Verify that your user has permission:
ls -l /dev/hidraw* | grep plugdev

Expected output:

crw-rw---- 1 root plugdev 239, 0 Aug  9 00:00 /dev/hidraw0

Step 4 – Browser Requirements​

  • Use Google Chrome or Chromium (Firefox does not yet support WebHID).
  • If using Chromium Snap version, connect these permissions:
sudo snap connect chromium:raw-usb
sudo snap connect chromium:hardware-observe
  • Enable WebHID support in Chrome (if not already enabled):
    1. Open Chrome and go to:
      chrome://flags/#enable-experimental-web-platform-features
    2. Set Experimental Web Platform features to Enabled
    3. Restart the browser

Step 5 – Connect via Fractal's Web Interface​

  1. Go to adjust.fractal-design.com
  2. Click Add Fractal USB Device
  3. Select Fractal Adjust Pro Hub – Paired
  4. Click Connect

If all steps were done correctly, the LED and fan controls should now work in Ubuntu directly from the browser.

Final Notes​

  • If the device still won't connect, check for other software that might be locking the HID device (e.g., OpenRGB).
  • You can debug WebHID in Chrome's DevTools console with:
await navigator.hid.getDevices()
  • Permissions must be set every time you add a new HID device, so repeat the udev rule creation for other devices.

✅ With these steps, the Fractal Adjust Pro Hub can now be controlled directly from Ubuntu's Chrome browser without root access.