Just got a word from the OPS here. Don’t update the MAC Thunderbolt yet. The last update forced by Apple, have a bug that, after it is done and rebooted, it will not let you to login and the disc image will need to be restored (in another words, it breaks the OS).
Looks like it only happens to a few users, either way, if you are willing to update your MAC, back-it-up first.
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