About a week ago Apple released a firmware update for Thunderbolt connections, which fixed stability issues when it was used in target disk mode. This update in general has been effective in most cases, but there are still users who are reporting problems when installing it or recognizing their thunderbolt units.
The first thing we should check is if our system is compatible, since although Apple has its updates available to users through the Mac App Store, restricting equipment for compatibility, they can also be downloaded manually from Apple's support section and these can be run on any system leading to misunderstandings although it is not installed but is compatible.
We must know how to distinguish between Thunderbolt and Displayport connections, this is because although the two have an equal physical connection a priori, they are different, while Thunderbolt supports the Displayport protocol It does not happen the same way in reverse, that is, from Displayport to Thunderbolt. To distinguish them we only have to look at the symbol that accompanies them, being a lightning bolt for Thunderbolt and a square with two vertical lines for Displayport.
The first tip to prevent greater evils would be to disconnect any device that uses the thunderbolt connection before applying the update. Later we should delete all residual files of other firmware updates, these are in the following path » System> Library> CoreServices> Firmware Updates «, and we will authenticate when emptying the trash.
The next is clear the cache of system updates that may have been stored, so we will open the terminal and enter this command:
open $ TMPDIR ../ C
When the temporary folder in question opens, we will look for the folder »Com.apple.SoftwareUpdate »And we will remove it directly. Finally just us there would be a general maintenance With a program such as CleanmyMac 2 or Onyx to finish tuning and in case of boot failures (it has occurred in some cases) we will perform a PRAM reset by pressing ALT + CMD + P + R at the same time when we start the Mac If this does not work, we should press CMD + R to enter recovery mode and try to repair the boot with the tools that will be given to us.
More information - Apple Releases Thunderbolt Firmware Update 1.2
Source - Apple Forums
