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Halvaldr Author

Level 1

4 points

USB SSD as a boot drive on MacBook Air 2012 / Failing to boot after few days

Hi,

recently internal SSD died on parents' MacBook Air 2012 and as the machine is otherwise fine and the Apple's internal SSD is not available in here, I chose to go with external SSD (as the laptop sits only on the desk really).

I installed Lion via Web Install, and gradually upgraded it to Sierra, as the newest compatible version of macOS. Everything worked well until today - after a restart the Macbook displays the Apple logo (the one with progress bar underneath, so, I presume, the OS loading screen), the progress will go to around 25% and then the laptop crashes.

As I am not near the machine, I cannot verify healthiness of the drive itself, but parents tried to unlplug everything and reset NVRAM and SMC

Does somebody know any reason for this behaviour? (except the rudementary ones, such as "dead drive, lol") :)

Thank you

MacBook Air

Posted on Dec 28, 2021 11:25 AM

Top-ranking reply

HWTech

Level 9

60,512 points

Posted on Dec 28, 2021 4:06 PM

After a PRAM Reset a Mac will default to attempt booting from the internal drive so you should destroy the partition table on the internal drive since it is also a tempting target for your parents to store items on it by accident. Your parents need to Option Boot the laptop and select the orange icon for the external boot drive. Then have them change the Startup Disk System Preference to the external drive so the laptop automatically boots to the external drive.

Have them try booting into Safe Mode to see if it will finish booting and logging in. If Safe Mode works, then it most likely means an issue with the Login items or a third party driver since these items are disabled. Plus Safe Mode runs a file system check and deletes some temp & cache files so sometimes a Mac may start booting normally after booting into Safe Mode.

It is possible the external SSD has a bad or loose cable, or maybe there is an issue with the USB port. Try using the other USB port.

It is possible the failing internal SSD is interfering.

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USB SSD as a boot drive on MacBook Air 2012 / Failing to boot after few days

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