How to Fix “Unlock iPhone to Use Accessories” USB Message

Nov 21, 2018 - 8 Comments

USB Accessory Unlock iPhone to use accessories message

If you have connected an iPhone, iPad, or iPod touch to a USB accessory, or even a Mac or PC lately, you may have seen an “USB Accessory – Unlock iPhone to use accessories” message appear on the screen (or “Unlock iPad to use accessories” for iPad of course).

This message appears on screen due to a new security feature introduced in iOS, which aims to better protect iPhone and iPad from unauthorized access attempts by USB connections. This is mostly a good thing, but until you approve the USB accessory and unlock the iOS device, you may find that the iPhone or iPad won’t communicate with the USB accessory, or it might not even charge.

Resolving the “Unlock iPhone to Use Accessories” Message with USB

The simplest way to resolve this message if you see it on the screen of your iPhone or iPad is to unlock the iPhone or iPad using your passcode, while the USB device or USB accessory is connected to the iOS device.

You may have guessed that already based on the message itself, but once you unlock the iPhone or iPad with a proper passcode, the message goes away, and the USB accessory or USB device will be able to communicate with the iOS device as intended, including charging the iPhone or iPad as intended.

How to Disable the USB Accessory Unlock Message on iPhone or iPad

If you connect many different USB devices and USB Accessories to an iPhone or ipad you may decide you don’t want to see that “Unlock to use accessories” message anymore, and no longer want to unlock the device every time to deal with this. You can disable this protective mechanism in iOS settings, but realize that doing so comes at a theoretical security risk since it will allow USB devices to connect to the iOS device without the iOS device being unlocked.

  1. Open the “Settings” app in iOS
  2. Go to “Face ID & Passcode” (or “Touch ID & Passcode”)
  3. Scroll down and locate the “USB Accessories” setting and toggle that ON to disable the USB security restriction protection
  4. How to disable USB accessory unlock iPhone message

By turning on the setting for “USB Accessories” you will no longer see the “USB Accessory – Unlock iPhone to use accessories” or “USB Accessory – Unlock iPad to use accessories” messages on the devices when connecting anything via USB.

If you have noticed that your iPhone won’t charge when plugged into some computers or devices and you’ve followed the usual troubleshooting steps to resolve charging issues, and the iPhone is running a modern version of iOS showing the ‘USB Accessory’ message on the lock screen, this very well could be the reason why.

What’s the point of restricting USB Accessories on iPhone or iPad?

Restriction of USB accessory attachments to the iPhone and iPad is a fairly new feature that is aimed at improving the security of iOS devices, by aiming to prevent unintended access of a device through any USB connection or USB mechanism.

A prominent example of what the USB security setting is aiming to prevent is something like the GrayKey box which is apparently used by some agencies and law enforcement bodies to gain access to otherwise locked iPhone and iPad devices, by revealing a devices passcode. But these capabilities are never limited, that’s just the nature of security flaws and exploits, and so if such a tool is available to the “good guys” then such a tool would also be available to the “bad guys” who could also gain unauthorized access to an iPhone or iPad, thus something like this poses a security risk.

Whether or not you want to keep the default setting with USB Accessories toggled ‘off’ or turn it ‘on’ as mentioned here so that you can avoid the message on your screen anytime a new untrusted USB devices is connected to the iPhone or iPad is entirely up to you, and a matter of your own security needs and privacy desires. For some users disabling the alert and USB restriction will be desired, whereas for others they might prefer the sense of security knowing that their device is inaccessible without authorization.

And of course if you turned this feature off so that you’d stop seeing the USB Accessory unlock message, you can always change your mind later, toggling this USB restriction setting off or on as needed in iOS. So perhaps if you’re planning a trip to a place where you’d be more concerned about prying eyes you could return to the default setting of restricting USB accessory access to an iPhone or iPad – it’s your call! If you feel like doing that, simply return to the same settings and turn ‘USB Accessories’ back off again.

How to enable USB restriction mode on iPhone or iPad

This USB security feature exists enabled by default on all iPhone or iPad models running iOS 12 and later, and was first introduced in iOS 11.4.1, but no earlier versions of iOS system software have the USB restrictions as an option, and also won’t display the message when a USB cable is connected to the iOS device.

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Posted by: Paul Horowitz in iPad, iPhone, Security, Tips & Tricks, Troubleshooting

8 Comments

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  1. Gordon says:

    Interesting, I have seen this multiple times on my iPhone X since updating to iOS 12 and it prevented it from charging all night.

    I understand wanting to limit data access, but shouldn’t it allow power to go through? Think about all the phone charging stations at airports, offices, stadiums, etc…

    • Derek Currie says:

      There are dongles available that can be put at the USB end of a charging cable which will block all data communication and only allow charging current. I would never connect any device for charging to a mystery charging port without one. Hacking devices via USB has become standard practice around the world. Look for PortaPow Data Blocker dongles. (I’d post a link, but it would likely cause this comment to be blocked).

      Meanwhile, there is a verified bug in iOS 12 that inadvertently turns off charging after period of time on certain iOS device models. It was supposedly solved with iOS 12.1. (It was only partially alleviated in 12.0.1).

      The way this is all supposed to work is documented by Apple in their article entitled “Using USB accessories with iOS 11.4.1 and later”. (Again, I’d post a link. But it triggers comment blocking).

    • Louie says:

      It IS supposed to allow power to go through, but it was a known issue with iOS 12 on the iPhone X, XS and XS Max that it wasn’t happening. Nonetheless, it has been fixed as of iOS 12.1, so download that update if you haven’t done so.

  2. Sean M says:

    It’s too bad that you can not just have the lPhone or iPad
    paired with a given numbers of computers so that when you plug into that computer you don’t get the error just like when you pair with your in car hands free stereo system with a passcode.

  3. Mary says:

    After researching for days why my iphone won’t connect with CarPlay (after upgrading to iOS 12), eventually I stumbled across this procedure. Now that my phone is unlocked, it works. Funny thing though, I never got any messages…the phone simply would not be recognized by CarPlay and it did before the upgrade.

  4. RM says:

    Excellent tip – I was hoping for a way around this when using third party cables. Thank you, and Happy Thanksgiving!

    • Curmoni Lonk says:

      I get this message when using Apple cables on iPhone to a computer…. won’t charge my iPhone without it then I have to ‘trust’ the computer even though it has been trusted a dozen times before.

      It just works?

  5. Big Brother says:

    Just came onto this article, sounds like they have already found a new way to sniff around your iPhone without your permission. Same as the USB thing? New?

    https://www.whio.com/news/local/local-law-enforcement-using-mysterious-new-tool-unlock-cell-phones/W9zAfzQXrFsJmOJjO04TJK/

    Welcome to the modern world.

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