After obtaining access to an attached device using navigator.usb.requestDevice I'm trying to open a connection with an attached device as follows:

device.open()
    .then(() => device.selectConfiguration(1))
    .then(() => device.claimInterface(1))

It seemingly successfully selects the configuration, however the claimInterface step will produce the following error:

DOMException: Unable to claim interface.

I'm running Chrome 55.0.2883.75 beta with the --disable-webusb-security flag as root (without those I didn't get any devices) on Ubuntu 16.10.

How can I get the connection up and running?

Edit:

It seems that the cdc_acm driver already claimed the interface since device I'm trying to attach is a serial device, unloading the driver will allow you to claim the device (however after this it plains about interface 1 not being available, as well as 0 or 2).

After obtaining access to an attached device using navigator.usb.requestDevice I'm trying to open a connection with an attached device as follows:

device.open()
    .then(() => device.selectConfiguration(1))
    .then(() => device.claimInterface(1))

It seemingly successfully selects the configuration, however the claimInterface step will produce the following error:

DOMException: Unable to claim interface.

I'm running Chrome 55.0.2883.75 beta with the --disable-webusb-security flag as root (without those I didn't get any devices) on Ubuntu 16.10.

How can I get the connection up and running?

Edit:

It seems that the cdc_acm driver already claimed the interface since device I'm trying to attach is a serial device, unloading the driver will allow you to claim the device (however after this it plains about interface 1 not being available, as well as 0 or 2).

• javascript
• google-chrome
• chromium
• webusb

• 1 Since this device has multiple interfaces we should make sure that you're claiming the right one. Please include the output of lsusb -v for your device which will list the full device descriptors. A USB CDC device will indeed be difficult to use with WebUSB because of the existing drivers that are loaded however forcing the driver to unload should release the interface. When you get an error like "Unable to claim interface" Chrome will provide possibly more detail about the error in chrome://device-log. – Reilly Grant Commented May 5, 2017 at 23:54

1 Answer 1

Once the configuration is selected, you can find the right interface number in device.configuration.interfaces[0].interfaceNumber:

device.open()
    .then(() => device.selectConfiguration(1))
    .then(() => device.claimInterface(device.configuration.interfaces[0].interfaceNumber))