I've got a mid 2012 MBP 13" in which I inserted a brand new MX100 in the place of the old HDD. I've put the old HDD in a case in the superdrive place and tried to install 10.10 but the install failed.

I then tried with th SSD in an USB case, managed to install & boot 10.10. Then I put the SSD back in the Mac and got the stop sign at boot.

At first I thought it was the Firevault on the HDD which was causing the issue but even after turning it off, the mac didn't want to boot...

Which brings me 2 questions:

  • Why does it boot when plugged in an USB case and not from inside?
  • How can I fix this thing?

2 Answers 2


To solve the problems we have to place the HDD on the original place. Then we place the SSD to the SuperDrive place. Just install Yosemite as usual and everything is working now.


I'm not sure about the former question without getting hands-on but here's a fix...

My usual advice - boot your Mac and download the 10.10 installer from Apple. Do not run the installer, cancel it. Next, build a USB installer from the 10.10 installer so you can perform a completely clean install. Take an 8GB USB stick and (very important) name it Untitled. Then run this command in Terminal...

sudo /Applications/"Install OS X Yosemite.app"/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/"Install OS X Yosemite.app" --nointeraction

It will take a few minutes to process so be patient.

When that's done, shut your Mac down and fit the SSD in its desired location. Then, start your Mac and hold the Option key to bring up the boot selector. Select the USB installer and proceed.

Once the installer has booted you can wipe the SSD using Disk Utility, partitioning it as GPT (in the Partition tab options) and format as Mac OS Extended (Journaled). Then let the installer do its thing and you should now have a properly bootable internal SSD. When that's done you will be given the option to migrate your data from the old drive, if that's what you want to do.

  • Didn't work, still the same crossed circle at the statup time. Mar 3, 2015 at 21:10
  • Did you follow all steps including booting from USB, running Disk Utility to partition the drive as GPT, before formatting as Mac OS Extended? Did the installer run as expected? If so then your drive connection should be ok. We've around 60 2012 13" MBPs and we've had 6 with failed HDD cables. The first symptom is the system will run really slowly if the drive is actually detected at all at boot time. If you put your HDD back in its original location can you boot from that ok? Mar 3, 2015 at 23:27

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