'No Access' issue booting from external drive.

GerryO

macrumors newbie
Original poster
Mar 24, 2019
2
0
Hi there! I have a 13" 2017 macbook pro, running High Sierra. I'm trying to boot a cloned Snow Leopard OS (Carbon Copy Cloner backup) from an external drive, but keep getting the 'Prohibited' / 'No Access' icon (see attached image) after I choose the drive in Startup Manager. I've tried this using a 4TB LaCie Thunderbolt RAID drive and a Samsung SSD T5, but neither get further than the No Access icon after Startup Manager. It works on my old 2009 13" MBP, but not on the 2017 MBP. Anyone any idea how I could fix this?
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GerryO

macrumors newbie
Original poster
Mar 24, 2019
2
0
The 2017 cannot run Snow Leopard due to a lack of drivers among other things.
Thanks for the reply. Any idea which modern MBPs can run it? I really need to be able to access older backups, so if it means downgrading, I’ll have to just do it.
 

CoastalOR

macrumors 68020
Jan 19, 2015
2,486
907
Oregon, USA
According to the Mactracker app the early 2011 MBP's shipped with Snow Leopard. WARNING: I would not recommend a 2011 15" or 17" MBP because they have a design flaw that caused the discrete GPU (dGPU) solder on the logic board to fail from heat. The only fix was to replace the whole logic board with the same design flaw. The 13" 2011 MBP does not have a dGPU and did not have that problem.

The link that @Audit13 posted from everymac was last updated in December 2010 and it probably missed the early 2011 MBP's
 
Last edited:

Fishrrman

macrumors P6
Feb 20, 2009
17,398
5,631
OP wrote:
"I really need to be able to access older backups"

If all you need to do is "get to your own files" on an older cloned drive with an older version of the OS, just plug in the drive, let it mount on the desktop, and "go after" the files that you need.

You don't have to "boot from it".
That's the beauty of a "cloned drive" -- it will "mount on the desktop" just as any other drive does.

BE AWARE:
There CAN be an issue with permissions when you mount an older drive (that had older user accounts) on a newer Mac.
This is EASILY overcome by doing this:
1. Mount the drive icon on the desktop. DO NOT "open it" yet.
2. Click ONE TIME on the drive icon to select it
3. Type "command-i" (eye) to invoke the "get info" box on the drive
4. At the bottom of get info, click the lock icon and enter your administrative password
5. In "sharing and permissions", put a check into "ignore ownership on this volume"
6. Close get info, and you're done.

You can now copy files from the old drive, and they will automatically "come under the ownership" of your NEW account on your newer Mac.