Webusb: Access Denied trying to open printer on Windows

Question

I am trying to allow a POS web app to print directly to a StarMicronics (or any receipt printer, for that matter) using the Chrome webusb API.

I am using the example

Answer 1

You get the "Access Denied" error on Windows because there is already a driver that has claimed the device. The Windows driver model requires that the "winusb.sys" driver be loaded for any device that will be accessed by a userspace application like Chrome.

See my answer to this earlier question about smartcard readers which encounter the same difficulty on Windows.