External Boot = No Entry Sign

Discussion in 'OS X Yosemite (10.10)' started by scrambler01, Oct 6, 2015.

  1. scrambler01, Oct 6, 2015
    Last edited: Oct 6, 2015

    scrambler01 macrumors newbie

    Oct 6, 2015
    Sorry if this is all been talked about here before but:

    I have been running Yosemite on and external Thunderbolt Lacie SSD and my mac mini for a while.

    Today I bought a new MBP with Yosemite installed. I wanted to boot off the same external drive.

    I could see it and select it but then instead of booting all I got was the 'no entry' sign- the circle with a diagonal line through it.

    I've try everything I can think of, including cloning the external drive to a traditional drive with USB connection.

    Same problem.

    PLEASE PLEASE, can anybody shed some light on this issue?

    Thanks in advance.

    OK, I think I've solved it. The slightly older version of Yosemite maybe doesn't run on the latest MBP chip/hardware. If you don't hear from me again it's because a simple OS update fixed the problem.
  2. chrfr macrumors 604

    Jul 11, 2009
    Yes, the newest computers will a special version of 10.10.3, or 10.10.4 or later. If any of your Macs are running any version of Yosemite earlier than 10.10.5, it's worth updating them.

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