MacOS 26 missing "Allow accessories to connect"

jichunz wrote:

Starting with the MacOS 26 official upgrade, I am getting warnings about connection from my Mac Mini M4 to an external USB-C monitor, "Accessory not enabled" "USB-C cable, using a displayport-capable cable and port to connect". It was working fine before the upgrade and continues to work after upgrade to MacOS 26.

When I search for solution, there are suggestions about looking into Settings -> Privacy & Security -> Allow accessories to connect. But the option is not available in MacOS 26.

What exact Mac Mini is this... an M-series?

If your Mac asks you to allow an accessory to connect

Allow USB and other accessories to connect to your Mac - Apple Support

if necessary Quit the System Settings and open it again.

Look at Displays and see if anything jumps out there(?)

When I search for solution, there are suggestions about looking into Settings -> Privacy & Security -> Allow accessories to connect. But the option is not available in MacOS 26.

That is only an option on laptops.

If it was that, you wouldn’t get any warning.

That warnings sounds more like it doesn’t recognize that it is a display and can’t understand why it is using DisplayPort. Does the monitor also send data over that USB-C port? If you can disable data over USB-C in the monitor, try that.