Symptoms
- Windows shows 'USB device not recognized' popup
- Device doesn't appear in File Explorer or Finder
- Device was working, then stopped after being unplugged and replugged
- Device works in one port but not another
Likely causes
- CommonFaulty or low-quality USB cableCheap or damaged cables can carry power but fail to carry data reliably.
- CommonUSB port providing insufficient powerSome ports, especially on hubs or the back of monitors, don't supply enough power for certain devices.
- CommonDriver issue or corrupted USB controller stateWindows can lose track of a USB device after a sleep/wake cycle or sudden unplug.
- PossibleDevice itself has failedExternal drives and older devices can fail electronically over time.
- Less commonToo many devices on one USB hubAn unpowered hub can run out of power capacity when several devices are attached.
What to do
- Unplug the device and plug it directly into a USB port on the computer, not through a hub or dock.
- Try a different USB cable if the device uses a removable one.
- Try a different USB port, including one on the back of a desktop, which often connects straighter to the motherboard.
- Restart the computer, since this resets the USB controllers and often clears the error.
- On Windows, open Device Manager, find the device (often under 'Other devices' with a warning icon), right-click and choose Uninstall device, then unplug and replug it.
- Test the device on another computer to determine if the device or the original computer is at fault.
- If it's an external drive, check whether it needs its own power adapter and confirm that's connected.
Tools and parts
- None
Replacement USB cableSearch: “USB-A to USB-C data cable”
When to call a pro
If a device is not recognized on multiple computers with multiple cables, the device itself has likely failed and should be replaced or professionally assessed if it holds important data.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.