"Allow Accessory to Connect" flashes up and disappears, SD card won't connect

Pretty sure this is, at least in my case, closely related to having multiple users logged-in, using fast user switching (where the desktop rotates on a cube when switching users). This "pops up and disappears" thing always seems to happen when I have two accounts logged-in.

Of course it always gets fixed with a reboot, but you shouldn't have to reboot to use a USB device, just because the "allow/deny" box, which should be front and center on the operational screen, popped up and then decided to hide itself in desktop compositor limbo.

If you've got multiple accounts logged in... does logging one out help? (Apple menu, "Log out Name...")

If you're not sure, check Activity Monitor and, under the CPU tab, scroll the table to the right side, and click the "User" column to sort. Then, check to see if there's another username besides yours, service accounts (starts with an underscore _), and "root" users. If there's another name (with lots of processes), there's another account active. If there's another name but it's only one or two, well... that's odd? Could be a clue.

If there's no other accounts logged in, then we're back to square one.

Wish it were possible to report issues like this to Apple, but it's definitely a bug, and quite an annoying one in certain situations.

You are right, it is caused by multiple logged in users. I logged out all other users except mine. Afterwards, the window pops up and waits for my confirmation. I did not need to restart. Thank you for the hint!

Indeed, same behaviour here under Sonoma 14.5 (23F79) and same workarounds, which are not totally satisfying:

• Disconnecting other users makes the dialog box stick around and not disappear
• Setting to security to "always" allow connect external devices also works

So this is quite obviously a widespread bug.

Yep, this was the exact issue in my case. Logging out one of my users, then reconnecting my keyboard allowed me to approve the permission prompt.

this worked for me: shut down the computer and then rebooting it in safe mode. plug in your usb accessory and the window to allow accessory should pop up and stay. Allow the accessory. Then restart the computer back to regular mode and it should work! :-)

It's been my experience that when I first see this message flash by (microsecond), if I unplug and replug about half a dozen times, it will start to stay apparent long enough for me to click "Allow."

A) I wish that this "flash in the face" event didn't exist in the first place

B) I wish that I could find the control in Settings to just turn it off.

flick harrison wrote:

I know I can turn off this security setting and get rid of this error. However, I don't really want to turn off a security feature to fix what seems like a bug.

Instead of "allow accessory to connect?" dialogue waiting for me to choose allow or cancel, the dialogue disappears instantly. Sometimes it pops up behind other things so i don't even know why my SD card won't connect until I switch apps and notice something the fifth or sixth time I tried to insert the SD.

How do I stop this glitch? Help y'all!

Then have a few suggestions ;

1 - Get Support Choose a product and we’ll find you the best solution.Start now and open an Apple Support Ticket as they are Apple Employees to deal will these types of issues . 

2 - Product Feedback - Apple and make it known to Apple regarding this ongoing issue 

For my work habits on 3 different M-Class computer, I am very aware when I am adding new or unknown USB accessor and am Expecting the System Alert

Thereafter action the System Alert accordingly - Allow or Deny

Can not duplicate this issue on the 3 Different M1 / M2 machines 😔

At least in my Workflow for reasons already shared

Then have a few suggestions ;

1 - Get Support Choose a product and we’ll find you the best solution.Start now and open an Apple Support Ticket as they are Apple Employees to deal will these types of issues . 

2 - Product Feedback - Apple and make it known to Apple regarding this ongoing issue 

I have the same issue. When inserting a USB device (in my case a Yubikey), the dialog pops up but disappears too fast to read or react to and automatically disallows the device. This bug forces me to allow all accessories, which isn't great from a security perspective.

Perhaps by reading the info in below link and adjusting your setting you can Always allow and never get this prompt at all

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

Perfect! This has been bugging me since I got this machine. Changing the security setting fixed it instantly. Thanks!