USB / Security setting issues - the security settings for USB ports cannot be changed to allow an accessory to connect.

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USB / Security setting issues - the security settings for USB ports cannot be changed to allow an accessory to connect.

Hello everyone, I'm hoping to find some answers related to these issues that have been popping up lately at my place of employment. Basically what happens is as follows:

1) Mac OS security settings are set to "Ask for new accessories", or whatever the default is, I'm pretty sure it's set to ask only for a new accessory.

2) The pop up alert for said accessory goes away, nearly instantly.

3) Changing the security setting to always allow does not allow the accessory to connect.

4) Changing the security setting to ask everytime makes the pop up come back, but you cannot click allow, the pop up goes away nearly instantly. You cannot click it, not even with an auto clicker.

5) These are M1-4 units, so NVRAM reset is not an option, but following the Apple guidelines to allow the SMC to reset does not work.

6) Reinstalling the OS does not work (done via the Mac OS recovery panel), the same port has the same product on a block list post OS install, initially I thought this might work if the security database is part of the OS, but since this didn't work, I suspect it's elsewhere in the firmware/BIOS equivalent on the system.

I've noticed this started to happen after OS 15 was released, but more frequently recently on more recent versions of this OS.

Has anyone encountered this, or found a solution?

Thanks! -Nex

Posted on Jul 10, 2025 1:16 PM

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Answer 1

Mac_Cat

Level 1

108 points

Jul 10, 2025 5:56 PM in response to Nexdeus88

Try this command line fix from a Terminal window:

Bypassing user authorization might be required for some environments. Device management services can control this behavior by using the existing allowUSBRestrictedMode restriction to always allow accessories.

Manage accessory access to Apple devices - Apple Support

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Answer 2

Nexdeus88 Author

Level 1

10 points

Jul 11, 2025 10:23 AM in response to Mac_Cat

Thanks for respond @mac_cat -

We have a multi-screen product for all laptops. On Macs with M1-3 in their basic form, they rely on DisplayLink for the second screen to function, and they are both connected via USB-C. On M1-3 Pro/Max they just function on USB-C (video from the port / laptop). M4 are just USB-C as well.

What I'm seeing happen is essentially the device is connected to these updated Macs, and one of the screens is not receiving power, video, data etc. The entire USB-C port just shuts it down, and won't allow it to connect. If I connect to the other USB-C port, it allows the device to connect. The port itself is fine (tested with other accessories, including another variant of a said multi-screen solution post "Allow all accessories"), the multi-screen solutions are working fine (tested on other Macs, and Windows laptops).

The best I can tell is because of that repeating security prompt just going away instantly, is that it's some sort of database write/read error, and it won't allow that particular entry to change, or a more base-level block, like from the BIOS equivalent or JAMF (or similar manged controllers).

I just moved, so once I get my PC up and running, I'm going to edit some footage real quick to show how the alert just pops up and rapidly disappears. Thanks again for your response. I appreciate you taking the time to check this out.

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Answer 3

Jul 10, 2025 7:17 PM in response to Nexdeus88

Are the systems in question Mac notebooks with Apple Silicon chips? Intel-based Macs, and Apple-Silicon-based desktop Macs, should always be allowing connection of new accessories.

If your Mac asks you to allow an accessory to connect - Apple Support

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Answer 4

Mac_Cat

Level 1

108 points

Jul 10, 2025 6:10 PM in response to Nexdeus88

I realize you are experiencing this on multiple platforms.

Do they have a common cable or hardware connection that are unrecognized?

What happens if you use an Apple device or Apple cable ?

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Answer 5

leroydouglas

Level 10

205,766 points

Jul 10, 2025 1:55 PM in response to Nexdeus88

Nexdeus88 wrote:

Hello everyone, I'm hoping to find some answers related to these issues that have been popping up lately at my place of employment. Basically what happens is as follows:

1) Mac OS security settings are set to "Ask for new accessories", or whatever the default is, I'm pretty sure it's set to ask only for a new accessory.

Make some changes and compare your results(?)

Then come back to your preferred settings and test...

Change it to "always" allow if this is an issue.

ref: If your Mac asks you to allow an accessory to connect - Apple Support

Verify your software is up to date…

The current stable release of Sequoia including bug fixes, security updates is macOS 15.5

Keep your Mac up to date - Apple Support

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Answer 6

Nexdeus88 Author

Level 1

10 points

Jul 10, 2025 2:01 PM in response to leroydouglas

Thanks for responding. Changing that setting does not allow the device to connect. It's as if the device is on a permanent block list, and that setting cannot be overwritten.

Something to note, if I set it to Ask Everytime, the device prompts the security alert, but it immediately goes away. It's as if the setting cannot be changed.

That's been part of my troubleshooting to see if we can force a re-authorization, but so far, no luck.

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