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Door staff@engadget.com (Roger Fingas) - 09 Nov 2026
The first thing to remember is that by default, macOS requires you to give permission for accessories to connect. This prevents malware from being injected. At the same time, if you accidentally reject a permission prompt, a legitimate accessory won't transmit data until you give the green light. Charging should still work in either direction.
Typically, you can force macOS to re-display the permission prompt by unplugging an accessory and plugging it back in again. To minimize future hassle, though, go to Apple menu > System Settings > Privacy & Security, then scroll down to the Accessories section. Here you can choose Ask for new accessories, Automatically allow when unlocked or Always allow. It's best to skip that third option unless you're always around your Mac or in a very secure environment.
If that doesn't change anything, you might want to verify that macOS sees your device in the first place. Hold down the Option key, then click on Apple menu > System Information. If you see the accessory listed under Hardware, you may need to check the manufacturer's online support info. If it's invisible, or if it's detected but you keep getting an error message when plugging in, there may be more we can help with.
A probable cause in that regard is power. Some accessories may require more than a Mac's USB port can supply, in which case you should get a related message, and there may be a separate power cable you need to plug in. If there's no separate power on your accessory, however, the USB port itself may be the issue. Try alternate ports on your Mac or connecting directly if you were using a hub or dock as an intermediary. If you keep getting power-related warnings, you may want to talk to Apple tech support — it could be that your Mac just isn't feeding power to USB.
Typically, you can force macOS to re-display the permission prompt by unplugging an accessory and plugging it back in again. To minimize future hassle, though, go to Apple menu > System Settings > Privacy & Security, then scroll down to the Accessories section. Here you can choose Ask for new accessories, Automatically allow when unlocked or Always allow. It's best to skip that third option unless you're always around your Mac or in a very secure environment.
If that doesn't change anything, you might want to verify that macOS sees your device in the first place. Hold down the Option key, then click on Apple menu > System Information. If you see the accessory listed under Hardware, you may need to check the manufacturer's online support info. If it's invisible, or if it's detected but you keep getting an error message when plugging in, there may be more we can help with.
A probable cause in that regard is power. Some accessories may require more than a Mac's USB port can supply, in which case you should get a related message, and there may be a separate power cable you need to plug in. If there's no separate power on your accessory, however, the USB port itself may be the issue. Try alternate ports on your Mac or connecting directly if you were using a hub or dock as an intermediary. If you keep getting power-related warnings, you may want to talk to Apple tech support — it could be that your Mac just isn't feeding power to USB.