Released June 2012, Model A1278. Intel processor with Turbo Boost, Up to 512 MB DDR5 Video RAM

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MacBook Pro Mid 2012

I am trying to change my internal hard drive to a 1TB SATA SSHD. I have tried to install a new os on the drive and boot up external connected to the machine and it works.

However if I take the 1TB drive and then insert into the machine and try boot up, i get a flashing folder with the question mark on it.

Answered! View the answer I have this problem too

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If your model is the Mid 2012 13" MacBook Pro with built-in DVD aka MD101, you should know that they burn through SATA-HDD cable like crazy. When this cable fails, it does exactly what you are describing: a flashing folder.

Another cause for the flashing folder is a bad disk. And and great way to diagnose this and isolate the issue to disk or SATA cable is to boot from USB to confirm working disk and OS. Which you just did.

So now you need to replace the SATA-HDD cable.

Here's a link to the replacement guide. It also has a link to the needed replacement part.

It is an easy job, just don't forget to disconnect the battery first and reconnect it last.

Bonus points: if your old HDD is still working, and you want to transfer your old system and softwares/applications and personal files, then after replacing the internal SATA-HDD cable:

1/ Mount the old HDD inside your computer and pull a time machine back-up to a spare/empty HDD that should have the same or more capacity than your existing data on the old HDD. For example, if your disk is the factory 500GB, and it contains 150GB of data, you need an empty disk with more than 150GB capacity to pull the time machine back-up. If your 500GB HDD is full, you will need an empty 500GB capacity disk. Once done, remove the old HDD and mount the SSHD in the computer, then restart your computer by pressing command+R and following the instructions to restore your time machine back-up.

2/ You might be able to install the SSHD inside your computer, connect your old HDD via USB, start your computer while pressing command+R, and use Disk Utility to restore your old partition to your new disk. Be careful to choose the source disk wisely, otherwise you risk deleting the source/old HDD.

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Thank you very much for the reply and help. This was what i was thinking it could be just weren't sure. Thank you for providing confirmation that this could be the issue.


I edited the answer with additional steps to keep your old system+data+apps.


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This is an error code that is being thrown because you do not have the proper programs on the drive if you have a computer tower that will take 2 drives you can put the old one in and transfer all the programs to the other drive this is a kinda confusing prosese to do and time consuming.

If you have any questions, concerns or help email me at or comment below!

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Thank you for reply. Is there another way that this could be done?


You could just buy a new drive with all the programs that you need or send the drive to someone that can do it.


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Cj Wellman will be eternally grateful.
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