A Stream Deck is attached, but it could not be opened. Mint 21.3

[Blknd-K9s]

Problem

• streamdeck sees the Stream Deck device but cannot open it:
  A Stream Deck is attached, but it could not be opened.
• /dev/hidraw* existed but hidapi/streamdeck could not access the device.
• Cause: Linux Mint 21.3 handles HID devices and USB permissions differently than Ubuntu. The default README udev rules are insufficient for Original V2 devices.

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Steps Taken and Why

1. Install dependencies

sudo apt install libhidapi-libusb0 python3-pip libxcb-xinerama0
python3 -m pip install --upgrade pip

• libhidapi-libusb0 → kernel library for HID communication.
• libxcb-xinerama0 → required for Qt to load X11 plugins.
• Upgrading pip ensures Python packages install correctly.

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2. Configure udev rules

File: /etc/udev/rules.d/99-streamdeck.rules:

SUBSYSTEM=="usb", ATTR{idVendor}=="0fd9", ATTR{idProduct}=="006d", MODE="0666", GROUP="plugdev"
KERNEL=="hidraw*", SUBSYSTEM=="hidraw", ATTRS{idVendor}=="0fd9", ATTRS{idProduct}=="006d", MODE="0666", GROUP="plugdev"

• The first line gives read/write access to the USB device node, which libusb or hidapi may query.
• The second line ensures all hidraw interfaces are readable/writable by the user.
• MODE="0666" → read/write for all users.
• GROUP="plugdev" → ensures standard users in the plugdev group can access the device.

Reload rules:

sudo udevadm control --reload-rules
sudo udevadm trigger

• Reloading and triggering ensures changes apply immediately.
• Unplug/replug the Stream Deck for the rule to take effect.

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3. Install Python hidapi and test access

python3 -m pip install --user hidapi --upgrade
python3 -c "
import hid
for device in hid.enumerate():
    if device['vendor_id'] == 0xfd9 and device['product_id'] == 0x006d:
        d = hid.device()
        d.open(device['vendor_id'], device['product_id'])
        print('Device opened successfully!')
        d.close()
"

• Ensures Python can communicate with the Stream Deck via HID.
• Confirms the udev permissions are correct.
• If this fails, StreamDeck-UI cannot work regardless of backend.

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4. Install Stream Deck GUI package

python3 -m pip install --user streamdeck

• Installs the GUI in the user environment (~/.local/bin).
• Avoids conflicts with system Python packages.

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5. Launch GUI with hidapi backend

STREAMDECK_BACKEND=hidapi QT_QPA_PLATFORM=xcb streamdeck

• STREAMDECK_BACKEND=hidapi → forces the application to use hidraw devices instead of libusb, which works on Mint.
• QT_QPA_PLATFORM=xcb → ensures Qt uses the X11 plugin, required for Mint Cinnamon.
• GUI now detects the device, allows editing buttons, and updates hardware.

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Key Insights

• On Mint 21.3, both the USB node and hidraw interface must be explicitly accessible.
• 0666 permissions plus plugdev group ensures Python and GUI can open the device.
• hidapi is the only backend guaranteed to work on Original V2 devices under Mint; libusb fails due to missing access to /dev/bus/usb.
  ** Worth noting that this took an EMBARRASSINGLY long time to resolve.