Message: Accessory Partially Enabled USB2 Controller Hub. How do I know which device it refers to?

the acid house wrote:

Hello,

I got this message the whole time:

https://discussions.apple.com/content/attachment/169b3ea6-0d8e-49da-bcc1-b820330c58ab

How do I know which device it refers to?

And when I know. What is the solution?

MacBook Pro 13" 2020 Four Thunderbolt 3 ports. with macOS 26.0.1 (25A362)

connected to a Apple Thunderbolt Display and there is a Apple Keyboard (US) (A1243) connected

I have no idea what's going on. It seems that the USB hub monitor isn't working properly under this new OS. I have another monitor that's the same, and I get the same error. In other words, it's not a broken hardware problem.

Thanks for your Help!

Try a different cable and compare your results.

The new macOS are increasingly fussy over sub-par cables for connecting external displays.

It is recommended to upgrade you cable connection using high quality cables certified ULTRA HDMI or PREMIUM ≤ 1.0 m length or USB-C Thunderbolt5 cables ≤ 0.5 m length cables rated for high-speed data.

This is known to resolve issues like yours, compare your results and report back.

The error message posted explains what you need.

If your Thunderbolt Display uses the old Thunderbolt 2 with mini-Display Port connector, then whatever adapter, dock, hub you are using to connect it to the laptop does not support the necessary display protocols since the error message specifically mentions using a "DisplayPort-capable cable and port". Whatever you are using is only acting as a very simple USB2 device.