Thunderbolt Firmware Update 1.2: Keeps reappearing and Thunderbolt ports and Target Display Mode may not work

  

After installing Thunderbolt Firmware Update 1.2:

  • Thunderbolt ports may not work.
  • Target Display Mode may no longer work.
  • The update may keep reappearing as available for download. 

This occurs when a self-powered Thunderbolt device (other than a directly-connected Thunderbolt display) is connected to a Thunderbolt port while installing the update.

To resolve this issue:

  1. Shutdown your computer.
  2. Disconnect all Thunderbolt devices.
  3. Wait 10 seconds.
  4. If you are using a Mac mini with a Thunderbolt display, reconnect the Thunderbolt display directly to your computer via the Thunderbolt port. Do not connect other Thunderbolt devices at this time.
  5. Restart your computer.
  6. If the Thunderbolt Firmware Update 1.2 is offered, download and install it and restart your computer when asked. If the Thunderbolt Update is not offered, the update has installed correctly.
  7. Reconnect all Thunderbolt devices.
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