everyday mac tools

"Allow accessory to connect?" on a Mac: what to choose and why

· 5 min read

“Allow accessory to connect?” is a real macOS prompt, not a scam. Mac laptops with Apple silicon show it when you plug in a USB or Thunderbolt accessory, or an SD card, that the Mac hasn’t approved before. Click Allow if it’s your own dock, drive or hub, and Don’t Allow if you don’t recognize it. Denying only blocks data: the accessory can still charge, or charge the Mac.

What the prompt protects against

A USB or Thunderbolt device isn’t only a power source. It can talk to the Mac, and some can pretend to be a keyboard or a storage device to get in. The prompt puts a person between the port and the device. Until you click Allow, the Mac doesn’t recognize the accessory or give it access to your data.

The prompt asks for approval in a particular way: your Mac has to be unlocked before you can approve an accessory. A device plugged into a locked laptop waits, and it can’t be approved by someone who doesn’t have access to the Mac.

The question under the title reads along the lines of “Do you want to connect the USB accessory to this Mac?” and swaps in “Thunderbolt accessory”, “SD card” or the accessory’s name depending on what you plugged in. The two buttons are Don’t Allow and Allow.

Which Macs ask

Apple documents this for Mac laptops with Apple silicon. Its article doesn’t mention desktop Macs or Intel laptops, so if your Mac mini or iMac never shows the prompt, nothing is wrong with it.

What each setting does

The choice lives in System Settings. Open the Apple menu, choose System Settings, click Privacy & Security, then scroll down and click Accessories. The menu there is Allow accessories to connect, with four choices:

  • Always ask. You approve every accessory, every time you connect it.
  • Ask for new accessories. You approve a new accessory once, the first time. This is the default.
  • Automatically allow when unlocked. Accessories connect on their own while the Mac is unlocked.
  • Always allow. Every accessory connects automatically. This switches the protection off.

For most people the default is right. You approve a new dock once and never see the prompt for it again. Pick Always ask only if you handle a Mac in places where strangers can reach its ports. Leave Always allow for a Mac that never leaves a locked room, and even then the default costs little.

Apple notes one catch: if the Mac has been locked for three or more days, you may need to unlock it before an accessory you approved earlier works again.

Charging still works

Denying an accessory doesn’t cut power. Apple’s article says accessories can still charge the Mac or charge themselves even if you choose Don’t Allow. So a power-only charger, a phone you’re charging from the Mac, or a charging dock is fine when you click Don’t Allow. What stops is data: the Mac won’t see a drive, a keyboard, a display or a network adapter on that port.

The prompt keeps appearing

If you chose the default and it still asks for the same accessory, check these:

  1. You clicked Don’t Allow once. Apple says the Mac asks again the next time you connect it. Click Allow when you do.
  2. The dock reconnects. A dock or hub can drop and re-attach its ports, and each one looks like a new connection. Check the cable and plug it into the Mac directly.
  3. The setting is Always ask. Switch back to Ask for new accessories.
  4. It really is a different accessory. A second device on the same hub is a new accessory to the Mac.

The prompt never appears and the accessory does nothing

A silent accessory is the other common complaint.

  1. Unlock the Mac. A prompt can’t be answered on the lock screen.
  2. Unplug the accessory, wait a few seconds and plug it back in.
  3. Open the setting above and check it isn’t set in a way that blocks you. On a supervised Mac, such as a work laptop, an administrator can control this setting, so you may not be able to change it.
  4. If the accessory shows “USB Accessories Disabled” instead of a prompt, that’s a different message with a different cause. See USB Accessories Disabled.

Reading a prompt before you click

Any permission prompt that appears right after you plugged something in is expected. A prompt you didn’t trigger is the one to question: ask what you did a moment ago. Reading a macOS permission prompt goes through that habit, and why a Mac blocks an app you downloaded covers a different layer of the same protection.

Questions

Should I click Allow on “Allow accessory to connect?” Yes, if you just plugged in something of your own, such as a dock, drive, hub or SD card reader. If you didn’t plug anything in, or the device isn’t yours, click Don’t Allow. You can approve it later by connecting it again.

Why does my Mac ask every time I plug in the same accessory? Either the setting is on Always ask, or you clicked Don’t Allow earlier, or the dock reconnects its ports. Set Allow accessories to connect to Ask for new accessories and plug the accessory in directly.

Will my Mac still charge if I click Don’t Allow? Yes. Apple says an accessory can still charge the Mac, or charge itself, when you deny it. Denying only blocks data.

Is it safe to set Allow accessories to connect to Always allow? It works, but it removes the check between your ports and any device that gets plugged in. For a laptop you carry around, the default is a better balance.