At times, if you attach an external USB device to the Windows 10 then an error message saying USB not recognized. Device Descriptor Request Failed pops-up on your screen. A device which is malfunctioned will be labelled as Unknown USB Device (Device Descriptor Request Failed) with a yellow triangle which indicates that your device is not working properly or USB is not recognized as it is already labelled as an Unknown USB device.
However, the USB descriptor is responsible for storing all the information which is related to various USB devices and also identifying these USB devices in the future when you connected it to the system. Though, if the USB is not recognized then the USB device descriptoris not working properly on your system. As a result, you will face the Device Descriptor Request Failed error.