Your USB Device Isn’t Showing Up on a Mac: Fixes to Try
When a USB accessory fails to appear on a MacBook, the cause is often a permission prompt, a power shortfall or a hub. Here are the macOS settings and hardware checks that can bring it back, in the order to try them.
When your USB device isn't showing up on a MacBook, the first thing to check is a macOS permission setting that can silently block data from a legitimate accessory. Power problems, hubs and out-of-date software are the other common culprits.
Modern USB accessories on the Mac are usually well-behaved. Occasionally macOS fails to detect one anyway. The fixes are often simple, particularly on the software side, though rare cases may need outside help.
Check the accessory permission first
By default, macOS asks for permission before an accessory can connect. The prompt exists to stop malware from being injected through a plugged-in device. If you reject the prompt by accident, the accessory will not transmit data until you approve it. Charging should still work in either direction.
Unplugging the accessory and plugging it back in usually brings the prompt back. To avoid repeat trouble, open Apple menu > System Settings > Privacy & Security and scroll to the Accessories section.
There are three options: Ask for new accessories, Automatically allow when unlocked, or Always allow. Skip the third unless you are always near your Mac or working in a very secure environment.
See whether the Mac detects it
Hold down the Option key, then click Apple menu > System Information. If the accessory is listed under Hardware, check the manufacturer's online support pages.
If it is invisible, or detected but throws an error each time you plug it in, move on to power and ports.
Power, ports and hubs
Some accessories need more power than a Mac's USB port can supply. In that case you should see a related message, and the device may have a separate power cable to connect. Without one, the port itself may be at fault, so try other ports on the Mac.
If you are using a hub or dock, connect the accessory directly to the Mac instead. Hubs and docks often need their own power supplies. Even when they do not, a chain of devices has to pass power or data across several hops, and any of them can fail.
One recent case involved a Thunderbolt dock. A wireless mouse receiver stopped working until it was plugged straight into the laptop, even though an SSD on the same dock worked fine. Skipping the middleman is safer when you have free ports.
If power warnings keep appearing, the Mac may not be feeding power to USB at all. Apple tech support is the next stop.
Update macOS and accessory software
Make sure macOS is current. Go to Apple menu > System Settings > General, then click Software Update. Bugs or driver compatibility problems could be interfering.
Some accessories also depend on proprietary software to function. Check the Mac App Store or the manufacturer's website for the latest version.
