Cannot Boot from External HD through USB-C Adapter

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Level 1

11 points

Cannot Boot from External HD through USB-C Adapter

I got my new 2016 15" MBPro today (Yeah!) and I tried to boot through the Apple USB-C to USB adapter and I am getting no luck. I get both HDs showing when I hold down the ALT key on boot, but when I select the external drive I get a circle with a slash through it.

I was planning on moving the data from the external HD to the new MBPro via SuperDuper.

I am moving the data through the migration assistant which seems to be working.

I also tried it on another adapter and a new powered USB-C Hub with the same results.

TIA!

MacBook Pro (15-inch, Late 2016), iOS 10.1.1

Posted on Nov 28, 2016 4:21 PM

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Answer 1

tjk

Level 9

51,192 points

Nov 28, 2016 7:43 PM in response to richjt92

Hi,

What do you have on the external HDD? Was it cloned to be bootable? From what? Another 2016? I suspect that's where the issue lies. Migration assistant is your best choice anyway.

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Answer 2

richjt92 Author

Level 1

11 points

Nov 29, 2016 4:04 PM in response to tjk

It was a 10.12 backup from my 2012 MacBook Pro. Not sure if it was 10.12.1 or 10.12.0. It was bootable on my 2012 MBPro.

The migration assistant worked, but I still want the ability to boot off an external in case I have issues.

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Answer 3

tjk

Level 9

51,192 points

Nov 29, 2016 4:09 PM in response to richjt92

Check to make sure all your data/settings etc. have migrated and are working. After that, just create a new SD clone to that HDD (don't remember if you have to first erase the old one or not, but it might be a good idea to, so you're starting clean).

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Answer 4

Nov 29, 2016 4:37 PM in response to richjt92

Recognized by Alt/Option boot says, "that one appears to be a bootable Volume"

"Circle with a slash" says that Volume is not bootable, typically because pieces are missing.

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Answer 5

markwmsn

Level 6

16,835 points

Nov 29, 2016 10:07 PM in response to richjt92

Generally, a Mac cannot be booted from a volume with a system older than that specific Mac model originally shipped with, because the Mac may have hardware that did not exist when the system was written. In this example, that would include the Touch Bar and Thunderbolt 3 ports; the software to drive them would be among the missing pieces Grant mentioned.

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