New MBP (touch bar) won't boot from external HD

OneSeventeen

You do NOT have "the same issue".

You need to start a NEW discussion with a title that can attract Readers who can help you. Be sure to supply as much information about that Boot Drive as possible.

It is the same issue. You should get to a boot screen at least even with el capitan. The only thing that won't work is installing an older software but the boot part should work.

i made a sierra boot volume using another toucher mac and the same issue happens.

So I made up a Sierra boot flash drive.

what version of Sierra is on that drive?

and are you trying to boot the 2016 or the 2017 model? The 2017 model requires Build 16F2073, or "purchased" 10.12.6 or better.

I had downloaded 10.12.6 from the App Store. Don't think its the version though. I've tried using a usb-c 3.0 adapter cable with a usb 3.0 flash drive; and I've tried using a usb-c 2.0 adapter cable with a usb 2.0 flash drive. Neither work. As far as I can see, you can't boot a 2017 macbook pro off an external flash drive at all. And Disk Utility no longer allows you to "burn" an image to a CD/DVD either. So it would appear that if anything happens to my SSD, my shiny new macbook pro will become a brick.

Update: I tried booting my MacMini off the USB3.0 flash. It wasn't recognized as a boot drive. I took it out and tried with my USB 2.0 flash, and it booted off that just fine. I had read somewhere that you couldn't use USB 3.0 for a boot flash drive, so I wasn't surprised. But this clearly means that the issue is with the Macbook Pro or with having to use a USB-C to USB A female adapter to connect the flash drive.

could it be it is not using a USB-C thumbdrive for the new macbook touchbar? i can't seem to boot it up with an adapter too. anyone tested this and works?

i am currently using the 2017 macbook pro touchbar 13inch

I have a new iMac (2017) and an older (2012) Macbook Pro, both running 12.5.6. I created a bootable external clone using Carbon Copy Cloner from a previous iMac. The clone was created with 12.5.5.

I can boot from the clone on the Macbook Pro, but cannot book from the (same) clone on the new iMac. I get the "prohibitory" symbol on the iMac's screen--a white circle with a line through it.

Thanks for any suggestions!

"A Mac can boot no version OLDER than the version it shipped with."

Often, a new computer ships with a "custom" version of the software, with special additions that bump its release number up higher than the "standard" purchased version from the store that appears to be the same version number.

If your new computer was running the "latest" version, you will likley have to download the Latest+ 0.1 version to build a "universal" external drive that boots both computers.

Apple used to have a document that detailed exactly which build was the "ships with" version for each recent computer, but has unhelpfully taken it down or removed it from public access. So we can no longer look up the exact build you would need.

Hi,

If you're really running El Capitan on the external, that's the reason why. The 2016 came with Sierra and cannot boot with an OS older than the one it shipped with.

Did you find solution, I am have the same issue!

That 2016 was created using Sierra not El Capitan. The 2015 was with El Capitan and can run Sierra. That's the way its always been.

I'm having the same issue with a Mac os Sierra boot disk using the Thunderbolt 3 to thunderbolt 2 adapter.

The version shipped with the 15-in 2016 MacBook Pro is a custom version of 10.12.1

Nothing short of "Purchased" 10.12.2 will boot that Mac.

Hi guys, i got the same issue although with external disk with bootable MAC OS Sierra 10.12.0. So, it is not only happen to bootable disk with el capitan.

I am having the same problem and thought it might be that too. So I made up a Sierra boot flash drive. Got the same thing, the prohibit sign. So its not due to the MacOS version.