Re: [pyusb-users] No Backend Available

[Jonas M. <jo...@pr...>]

On Wed, Jan 20, 2021 at 6:20 PM Steve Kranish via pyusb-users
<pyu...@li...> wrote:
>
> This is a widely reported problem which has just been left dangling for
> many people. I have yet to see a complete, meaningful resolution.

This is not true.

The solution, as you have already gathered, is to install libusb.


> Almost no one mentions what versions of what they are using..

By the way, you haven't mentioned whether you're running 32 or 64 bit
Windows and Python.


> I have libusb-1.0.dll in c:\windows\system32 AND the directory where my
> python script exits. I still get the “No backend available” error.

Once common 64-bit Windows problem is that 64-bits DLLs go in
C:\Windows\System32 while 32-bit DLLs need to go in
C:\Windows\SysWOW64.

Perhaps that's your issue?


> dev = usb.core.find(backend=backend, find_all=True)
> File
> “C:\Users\skranish\AppData\Local\Programs\Python\Python38\lib\site-packages\usb\core.py”,
> line 1297, in find
> raise NoBackendError(‘No backend available’)
> usb.core.NoBackendError: No backend available
>
> This must be dependent on SOMETHING ELSE that needs to be installed.

Nope, sorry.


> Perhaps in some installations, is installed by default, and in other
> installations it is missing.
>
> Windows 7, Python 3.8 (required for W7)
> libusb 1.0.23b7
> pyusb 1.1.0