Windows 8.1 64bit doesn't recognise Arduino UNO

Hi folks,

I’ve bought a Arduino UNO yesterday but its not working properly.
In the Device Manager its displayed as “Unknown USB Device (Device Descriptor Request Failed)” and if i try to install the driver (yes i disabled the driver signature thing by rebooting with advanced settings) and it just keeps telling me that the Driver for “Unknown USB Device (Device Descriptor Request Failed)” is up to date… I also tried another USB cable and port…

Do someone have a clue what i can try?



I’m sending a screenshot from my Windows 8.1 x64 (which works OK), maybe it helps somehow.
I see no other device in device manager except the item in the screenshot.

Thanks for your screenshot but actually its not really helpful...
Is it possible that i just bought a defect Arduino??

The same trouble with Arduino (I’ve got Leonardo). Under Windows 7 64-bit Windows don’t wanna install properly driver for the board. And there’s no COM port at all.
But there are no problems under Windows 8 32-bit and Windos XP 64-bit with installation.

There’s one main problem at all! There’s no output to port monitor window! Please tell me why the script doesn’t work?

void setup() { Serial.begin(9600); while(!Serial);}
void loop ()
for ( int i=0; i<10;i++)
Serial.write (“any text…”);
delay (10000);

All USB ports (2.0) where tested all kind of USB-cables I’ve got where tested (various length)…
But the problem still exists!