I’m working on a Python project that needs to communicate with a USB NFC reader. I decided to use PyUSB for this task but I’m running into a frustrating problem.
Whenever I try to run my code, I get this error:
ValueError: No backend available
After some debugging, I found that the issue is in the usb/backend/libusb10.py file. It’s looking for a file called libusb-1.0.dll but this file doesn’t exist on my system.
I already installed libusb-win32 from SourceForge, thinking that would solve the problem. However, the installation only gave me libusb0.dll, not the version 1.0 DLL that PyUSB wants.
Has anyone dealt with this before? I’m running Windows 7 and just need to get PyUSB working properly. Either I need to find the right DLL file or maybe there’s a different approach I should try.
You installed libusb-win32, but that’s your problem. It only comes with libusb0.dll (the old 0.1 API), and PyUSB needs libusb 1.0. Go to libusb.info and grab the official libusb 1.0 binary instead. Extract libusb-1.0.dll from either the MS32 or MS64 folder (match your Python architecture) and drop it in your system PATH or project folder. I had the same issue with a card reader and this fixed it right away. Just make sure the DLL architecture matches your Python install.
had the same headache with a barcode scanner last month. the libusb-win32 thing trips everyone up - it’s completely different from what pyusb wants. just run pip install libusb-package instead of manually dealing with dll files. it handles the backend automatically so you don’t worry about file placement or architecture mismatches.
Oh interesting! what Python version r u using? Backend issues can be architecture-related - check if you’ve got a 32-bit/64-bit mismatch between Python and your system. Also, does your NFC reader work with other software or is this ur first time connecting to it?