Leonardo not recognised

Hi all,

I have just bought a clone Leonardo from Core and am having a lot of trouble getting it to be recognised by my PC. If I leave it disconnected from my PC for awhile it will connect but fails to upload sketches and if reset, will no longer be identified.

It will accept sketches when programmed with an external programmer but I need it for its ability to act as a USB keyboard.

So far I have tried;

  • Older versions of IDE
  • Several different drivers (no VID or PID so can't assign most times)
  • Bought a programmer and tried several bootloaders
  • 3 different PC's and a Linux system
  • Several known working cables
  • Reset via pins
  • Set up as keyboard to see if it is recognised

  • I have spent hours on this and am out of ideas. My same brand Nano works fine on my PC.
    Any ideas? Thanks,
    1 Like

    Are you installing the Arduino IDE, or using the portable version?

    If using the portable (.zip download) you’ll need to install the USB drivers for the 32u4 manually. They’re in the drivers sub folder in the arduino directory

    1 Like

    Regular version.

    I also just tried full uninstall and re install. Found the device and installed drivers.

    Tried uploading ‘Blink’ and got an error. Started upload and hit reset button, result is this;


    1 Like

    Hmm, did a quick bit of googling for you; two possibilities I found:

    1. Windows driver signing
    2. Selected wiring board and corrupted it

    (Scroll down to the response from Majenko)


    Tried the driver signing and I bought the board from Core so I hope it isn’t that cheap that basically D.O.A.

    I just completely reset my PC and tried a few things again. Same error. It has to be the board at this stage. Thanks for your help Oliver.

    1 Like

    Here’s a thread from Adafruit’s forums that sounds very much like your issue. They got it working by a similar method to the one the guy on stack exchange described.



    Hi Chris,

    Did you manage to get this working with any of the steps the other Oliver suggested? If not, please send us an email (just hit Reply on your order confirmation/invoice email) with a link to this forum topic and the details of anything else you’ve tried so far and we’ll get this sorted for you ASAP!

    Support | Core Electronics