MacBook Pro 2012 13" Prohibitory symbol after format | Unbootable?

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MacBook Pro 2012 13" Prohibitory symbol after format | Unbootable?

I have the Prohibitory symbol, I accessed the disk utility through 'command+R' I tried to back up my data on an external hard drive via USB. I created a image on the formatted hard drive that was larger than the internal hard drive. I then proceeded to restore/backup by selecting the internal disk as source and NOT the .dmg but the image file as the source. After multiple errors 254 and trying to verify and repair disk I decided to simply format everything and install a new OS X.

I go through internet recovery mode access disk utility (cmd+R) and format the disk (a number of times now) and install the newest OS. I wait for the restart and I still get the Prohibitory symbol. I have tried to verify and repair the disk, it displays that not all information can be given. Sometimes the verify/repair does not display any error message after format so I proceed with installing the new OS X. Still get a Prohibitory symbol. Do i change the format type from 'MAC OS Extended Journaled to MS-DOS'?

I'm starting to believe that it is the HDD cable, perhaps even the HDD. I have opened the macbook and made sure that the HDD cable was secure. The macbook has not had any issues with the HDD or Prohibitory symbol in the past. I only changed the battery about a year ago. Anyhow I believe the system simply does not recognize the (unmounted) disk, as one time the internal HDD did not display in the disk utility. The only thing present was the Base OS drive (unbootable)

Any and all info would be appreciated!

MacBook Pro 13", macOS 10.14

Posted on Jan 31, 2020 11:35 AM

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Answer 1

Top-ranking reply

Kappy

Level 10

361,849 points

Jan 31, 2020 11:54 AM in response to Vaincre

Prohibitory symbol

A circle with a line or slash through it means that the selected startup disk contains a Mac operating system, but it's not a macOS that your Mac can use. You should reinstall macOS on that disk.

You cannot boot from a .dmg image of a bootable system. A bootable disk must be write-enabled. You cannot write to a disk image file, hence, it is not bootable. What you need is called a clone. You can clone an existing system using Disk Utility but only when booted from the Recovery HD or another disk.

There is only one way you might test the HDD, and that would be to run the Apple Hardware Test: Apple Hardware Test.

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Answer 2

John Galt

Level 10

146,210 points

Jan 31, 2020 11:58 AM in response to Vaincre

How did you format the startup disk? GUID Partition Map and Mac OS Extended (Journaled) are both required. If you want to install Mojave or Catalina choose APFS.

Do i change the format type from 'MAC OS Extended Journaled to MS-DOS'?

No, that won't help at all.

I'm starting to believe that it is the HDD cable, perhaps even the HDD.

Me too. Given the symptoms and everything you did to address them, I surmise the HDD has failed. They have become very inexpensive to replace.

Consider it an opportunity to replace it with a solid state drive. If you choose to do that I personally recommend OWC / MacSales. Many aftermarket SSDs obtained from PC-centric vendors will perform poorly or simply won't work on Macs. OWC knows what they're doing.

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Answer 3

Kappy

Level 10

361,849 points

Jan 31, 2020 12:09 PM in response to John Galt

"Many aftermarket SSDs obtained from PC-centric vendors will perform poorly or simply won't work on Macs"

John,

This is not entirely true. Some third-party SSDs are incompatible with Macs. Most were from Western Digital, although this is less the case today. The only real problem is formatting. PC-centric vendors may pre-format the disks using a Microsoft format. All one need do is reformat the disk on the Mac using the GUID partition scheme and using APFS, if running Catalina, or HFS+ for pre-Catalina systems.

I have purchased many third-party SSDs. Except for those from OWC, they were unformatted. OWC did pre-format for the MAC but I haven't bought a new 2.5'' SSD from them recently, so I don't know if that is still the case. I have found that OCZ makes the most compatible and reliable notebook SSDs.

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MacBook Pro 2012 13" Prohibitory symbol after format | Unbootable?

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