Solution: Apple Thunderbolt Display brightness control doesn’t work anymore

Apparently, there’s a macOS bug that if your Mac has been connected to a Thunderbolt Display for a long time, the brightness of the display can no longer be adjusted (neither by pressing the according F1/F2 keys on your keyboard nor by using the brightness slider in the display settings of the system preferences).

The simple yet surprising fix is:

  1. Unplug your Thunderbolt Display’s Thunderbolt cable, and plug it in again
  2. The display’s brightness will be adjustable again



17 Replies to “Solution: Apple Thunderbolt Display brightness control doesn’t work anymore”

      1. Mine either (both of them) and when I connect, I don’t have ethernet through the display either. This was working perfectly 2 weeks ago.

        1. To change the brightness of your Thunderbolt/LED Cinema Display, press CTRL and F1/F2.

          Note that you must have the USB cable plugged into your laptop for this to work properly.

  1. Damn!! it worked!! thanks a lot!!! I had headache while using this display and I think reducing the brightness will help me.

  2. Same issue. Thunderbolt display lost brightness. Unplugged everything twice. Had to enter System Settings-Display Presets-Thunderbolt Display-Brightness.
    Working now!

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