Why your USB device is not showing up on your MacBook and how to fix it

USB wouldn’t be what it is today without Apple. The form factor predates the iconic original iMac, but Apple’s gumdrop computer helped popularize it by ditching all the old connectors that haunted the industry. USB has become so common, in fact, that the pressure has returned to the company, with European Union regulations forcing it to ditch Lightning ports on iPhones. The days of Apple-exclusive ports are effectively over, with MagSafe being the main remaining obstacle.

Modern Mac USB accessories tend to perform well. However, sometimes macOS fails to detect them, which is understandably infuriating. With USB being as widespread as it is, anything less than a seamless experience seems unacceptable.

The good news is that there are known hardware and software explanations for why this happens, such as damaged cords or an accessory requiring more power. In many situations, fixes are remarkably simple, especially on the macOS side. There are, however, rare cases where you may need to seek outside help.

The first thing to remember is that by default, macOS asks you to allow accessories to be connected. This prevents malware injection. At the same time, if you accidentally reject a permission request, a legitimate prop won’t transmit data until you give the go-ahead. Charging should always work in both directions.

Typically, you can force macOS to redisplay the permission prompt by unplugging an accessory and plugging it back in. However, to minimize future hassles, go to Apple Menu > System Settings > Privacy & Securitythen scroll to Accessories section. Here you can choose Request new accessories, Automatically allow once unlocked Or Always allow. It’s best to ignore this third option unless you’re always near your Mac or in a very secure environment.

If that doesn’t change anything, you may want to verify that macOS sees your device in the first place. Hold down the Option key, then click Apple Menu > System Information. If you see the accessory listed under Materialyou may need to consult the manufacturer’s online support information. If it is invisible or detected but you continue to receive an error message when plugging in, we may be able to help you further.

A probable cause in this regard is power. Some accessories may require more than a Mac’s USB port can provide, in which case you should receive an associated message and may need to plug in a separate power cable. If there is no separate power supply on your accessory, however, the USB port itself may be the problem. Try other ports on your Mac or connect directly if you’re using a hub or dock as an intermediary. If you continue to receive power-related warnings, you may want to speak to Apple Support. Your Mac may simply not be receiving power from the USB port.

Speaking of hubs and docks, remember that these often require their own power supply. And even if it doesn’t, things can go wrong with device chains, because of course they have to successfully transmit power or data over multiple hops. We recently had an experience with a Thunderbolt dock in which a wireless mouse receiver became unusable until plugged directly into a laptop – not to mention the fact that an SSD on the dock worked just fine. It is always safer to avoid middlemen if you have enough free ports.

Make sure macOS is fully up to date by going to Apple Menu > System Settings > Generalthen clicking on Software update. Bugs or driver compatibility issues could hypothetically interfere. Some accessories may also rely on proprietary software to do a lot of things, in which case you should make sure you have the latest version of this installed. Check the Mac App Store or a manufacturer’s website. External cards and drives must use file system formats compatible with macOS, namely APFS, FAT, or ExFAT.

Finally, make sure you’re using the right type of USB cable for a device’s power and bandwidth needs and that no damage or debris is interfering with the cables or ports. Things like lint and bent pins can be enough to stop something from working. Lint, dust and grime can usually be cleaned with a can of compressed air or by gently running a soft-tipped tool. As for damage, you’ll probably just need to replace a new cable, especially if there are signs of browning or exposed wires. These indicate a risk of fire.