macOS USB Device Not Recognized Fix

What Does This Error Mean?

When your Mac does not recognize a USB device, the device does not appear in Finder, System Information, or on the desktop. This can happen with USB drives, keyboards, mice, hubs, and any other USB-connected device. The most common causes are a faulty cable, a USB hub that cannot supply enough power, a corrupted USB driver, or a system setting that needs resetting.

Affected Models

MacBook Air
MacBook Pro
iMac
Mac Mini
Mac Pro
Mac Studio

Common Causes

The USB cable is damaged, low quality, or not fully seated in the port
A USB hub is not supplying enough power for the connected device
The Mac's USB driver or USB controller has crashed and needs to be reset
The device is formatted with a file system that macOS cannot read (such as Linux ext4)
macOS privacy settings are blocking the device from mounting (especially for MIDI or audio devices)

How to Fix It

Try a different cable and a different port. Unplug the device and try a different USB-C or USB-A cable. Also try connecting directly to the Mac instead of through a hub.

A faulty cable or underpowered hub is the cause of the majority of USB recognition failures. Always test the simplest physical issues first.
Check System Information to see if the Mac detects the device at all. Go to Apple menu > About This Mac > More Info > System Report. Under Hardware, click USB. Look for the device in the device tree.

If the device appears in System Information but not in Finder, the issue is a software or format problem. If it does not appear at all, it is a physical or power problem.
Reset the USB driver by restarting the USB controller. Open Terminal (Applications > Utilities > Terminal) and type: sudo killall -STOP -c usbd — wait a few seconds, then type: sudo killall -CONT -c usbd

This restarts the USB daemon without rebooting. It often fixes temporary USB recognition failures.
Reset the SMC (System Management Controller). On Intel Macs with a T2 chip: shut down, then hold Control + Option + Shift for 7 seconds, then also press the power button for another 7 seconds, then release and press power normally. On Apple Silicon, a simple restart resets equivalent functions.

The SMC controls USB power delivery. Resetting it resolves many USB device power and recognition issues on Intel Macs.
Check if the drive needs reformatting. If the USB drive appears in Disk Utility (search for it in Spotlight) but not in Finder, the file system may be incompatible. Back up the drive if possible, then use Disk Utility to erase and reformat it as APFS or ExFAT.

ExFAT works on both Mac and Windows. APFS is Mac-only but better for Mac-only use.

When to Call a Professional

If no USB devices work at all and resetting the SMC does not help, a Mac's USB controller may have failed. This is a hardware issue that requires service — contact Apple Support or an Apple Authorized Service Provider.

Frequently Asked Questions

My USB drive shows in Disk Utility but not in Finder. Why?

If a drive appears in Disk Utility but not in Finder, it usually means the drive is not mounted — either because of a file system error, or because the volume did not mount automatically. In Disk Utility, click the drive and look for a Mount button. If mounting fails, run First Aid on the drive to check for and repair file system errors.

Does macOS support NTFS drives used with Windows?

macOS can read NTFS drives (the Windows file system) but cannot write to them without additional software. If you need to use a drive on both Mac and Windows, format it as ExFAT — both systems can read and write ExFAT natively. If you only need to copy files off an NTFS drive onto a Mac, no extra software is needed — it will appear in Finder in read-only mode.

None of my USB devices work after a macOS update. What happened?

Occasionally a macOS update introduces a bug that breaks USB functionality. Check the Apple Support pages and community forums to see if others are reporting the same issue. If it is a known bug, Apple typically releases a supplemental update quickly. In the meantime, resetting the SMC and restarting the Mac often restores USB functionality until the patch is released.