Unknown USB Device (Device Descriptor Request Failed): what it means and the fix

Unknown USB Device (Device Descriptor Request Failed) in Device Manager on your second PC means Windows saw something plugged in, but couldn't read what it is. Windows may also pop up USB device not recognized, and the device's properties may show Code 43. It isn't a missing driver. Windows gets stuck before it can even pick one. With a DMA card it's usually the cable, the USB port or a stuck card.

How to fix it

Work down the list and check Device Manager after each one.

• Use a different rear USB 3 port.
  Unplug the cable and plug it into another port on the back, with no hub. Front and top ports go through a cable inside the case and can cause dropouts.
• Use the cable from the box.
  Push it in fully at both ends, and flip the USB-C plug over at the card end. A lot of USB-C charging cables only have USB 2.0 wiring inside, so don't swap in one of those.
• Cold boot the main PC.
  The card gets its power from the main PC, and a card stuck after a restart or sleep can answer badly. Cold boot has the steps.
• Remove the unknown device.
  In Device Manager, right-click Unknown USB Device (Device Descriptor Request Failed) and choose Uninstall device. Unplug the cable, then plug it back in.
• Turn off USB selective suspend.
  Power settings on your second PC shows where it is.
• Try another computer, like a laptop, if you have one. If the card shows up fine there, it's the second PC's ports.

What you should see

On the data port, once the driver is in, it's FTDI FT601 USB 3.0 Bridge Device under Universal Serial Bus controllers. Before the driver, it's FTDI SuperSpeed-FIFO Bridge under Other devices. That's progress: Windows can read the card now, and one button in MewTools fixes the rest. On the JTAG port it's USB To UART+JTAG until the JTAG driver is in. What Device Manager shows has every state.

Still unknown on every rear port? Open a ticket in our Discord with a screenshot of Device Manager and a photo of the card's lights. Hardware we sold you has three months of warranty. Other errors are in DMA error messages.