Re: [libusb] DOMException: Failed to execute 'controlTransferIn' on 'USBDevice': A transfer error has occurred.

[Xiaofan C. <xia...@gm...>]

On Sat, May 4, 2024 at 5:06 PM <jo...@be...> wrote:
>
> I’m trying to use libusb in a Qt WebAssembly app via the Emscripten port.
> It’s a port of driver that works under Linux & Windows. The first call to
>  libusb_get_device_list() is failing with the console message:
>
>     DOMException: Failed to execute 'controlTransferIn' on 'USBDevice':
> A transfer error has occurred.
>
> On Windows 11 using Chrome, Edge and Opera.
>
> Tracing through the code, in emscripten_webusb.cpp makeControlTransferPromise()
> calls controlTransferIn with "request_type”: “standard", "recipient”: “device", "request”: 6,
> "wValue”: 0x100, "wIndex”: 0, "wLength”: 0x12 before this error.
>
> Any idea why this might be failing? If I perform the same controlTransfer in
> JavaScript, it works OK.

As per libusb Wiki, the status of WebAssembly + WebUSB support is EXPERIMENTAL.
https://github.com/libusb/libusb/wiki

The above Wiki has a link to the following blog post which talks about the
difficulties in enumerating the devices using web applications.
https://web.dev/articles/porting-libusb-to-webusb#using-the-port

If that does not help, please create a new issue in libusb github.
https://github.com/libusb/libusb/issues

-- 
Xiaofan