MacOS – Guide to Fix Broken GPT, GUID and Unmountable, No Type Volumes

efiguidmacbook promacosmount

I have a Macbook Pro with retina, Yosemite and 500GB hard drive.
I tried to install Windows using Bootcamp and accidentally deleted a partition, now my Mac cannot boot anymore.
This is the output from sudo gpt -r show disk0

  gpt show: disk0: Suspicious MBR at sector 0
    start       size  index  contents
        0          1         MBR
        1          1         Pri GPT header
        2         32         Pri GPT table
       34          6         
       40     409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
   409640  776617328      2  GPT part - FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF
777026968    1269760      3  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
778296728        616         
778297344  198807552      4  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
977104896        131         
977105027         32         Sec GPT table
977105059          1         Sec GPT header

I only need to make the second partition at index 2 and type FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF to be bootable again. This partition has FileVault 2 enabled.

But right now, I have no clue on what to do.

P/S: I Followed the instruction from @klanomath
Boot from a external hard drive with full Yosemite system
but at the last command to change the partition type

sudo gpt add -b 409640 -s 776617328 -i 2 -t 53746F72-6167-11AA-AA11-00306543ECAC /dev/disk0

It got this error:

gpt add: /dev/disk0: Suspicious MBR at sector 0
gpt add: /dev/disk0: error: no space available on device

This is the output from sudo gpt -r show /dev/disk0

   gpt show: /dev/disk0: Suspicious MBR at sector 0
     start       size  index  contents
         0          1         MBR
         1          1         Pri GPT header
         2         32         Pri GPT table
        34          6         
        40     409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
    409640  776617328      2  MBR part 218
 777026968    1269760      3  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
 778296728        616         
 778297344  198807552      4  MBR part 175
 977104896        131         
 977105027         32         Sec GPT table
 977105059          1         Sec GPT header

Progress:

I have executed command sudo gpt destroy /dev/disk0

But when I tried to add the first partition back using this command sudo gpt add -b 40 -s 409600 -i 1 -t C12A7328-F81F-11D2-BA4B-00A0C93EC93B /dev/disk0

I got this error straight away

gpt add: /dev/disk0: Suspicious MBR at sector 0
gpt add: /dev/disk0: error: no primary GPT header; run create or recover

Now the command sudo gpt -r show /dev/disk0 gives me this

   gpt show: /dev/disk0: Suspicious MBR at sector 0
     start       size  index  contents
         0          1         MBR
         1     409639         
    409640  776617328      2  MBR part 218
 777026968    1269760      3  MBR part 175
 778296728        616         
 778297344  198807552      4  MBR part 175
 977104896        164

Progress 2:

I executed sudo gpt create /dev/disk0
and got this error:

gpt create: /dev/disk0: Suspicious MBR at sector 0
gpt create: /dev/disk0: error: device contains a MBR

and I executed this command sudo fdisk -i -a hfs /dev/disk0 to write new MBR
and executed sudo gpt create /dev/disk0 again but got the same error gpt create: /dev/disk0: error: device contains a MBR

Now sudo gpt -r show /dev/disk0 gives me this

      start       size  index  contents
      0          1         MBR
      1         62         
     63  977104997      1  MBR part 175

Progress 3 and final 😀

Firstly a big thank to @klanomath, without the help, I couldn't go this far.

I executed this command sudo gpt create -fp /dev/disk0

And this command sudo gpt recover /dev/disk0 to get the secondary GPT header

After that, I executed sudo gdisk /dev/disk0 and the disk is mounted and functions properly

Best Answer

The content type of the second partition is wrong. Instead of FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF it has to be 53746F72-6167-11AA-AA11-00306543ECAC.

To edit the content type you have to boot to Internet Recovery Mode and use gpt. Additionally the fourth partition will be removed (probably the "deleted" partition). Please check that it doesn't contain any data!

Preparation:

Detach any external drive (especially your external Time Machine backup drive)
Restart to Internet Recovery Mode by pressing alt cmd R at startup.

The prerequisites are the latest firmware update installed, either ethernet or WLAN (WPA/WPA2) and a router with DHCP activated.
On a 50 Mbps-line it takes about 4 min (presenting a small animated globe) to boot into a recovery netboot image which usually is loaded from an Apple/Akamai server.

I recommend ethernet because it's more reliable. If you are restricted to WIFI and the boot process fails, just restart your Mac until you succeed booting.

Alternatively you may start from a bootable installer thumb drive (preferably Yosemite or El Capitan) or a thumb drive containing a full system (preferably Yosemite or El Capitan). If you boot to a full system and login as admin you have to prepend sudo to execute special commands like gpt ...!

Remove the fourth partition and change the content type of the second partition

Booted to Internet Recovery Mode open Utilities → Terminal in the menubar and enter: diskutil list to get the disk identifiers. Below I assume that your main disk has the disk identifiers disk0.
First you have to remove the fourth partition (only do that if it is really empty!):
```
gpt -r show /dev/disk0 #to get an overview
```
To delete a partition with gpt the disk has to be unmounted:
```
diskutil unmountDisk /dev/disk0
gpt remove -i 4 /dev/disk0 #remove the fourth partition
```

Then you have to change the content type of the second partition:

diskutil unmountDisk /dev/disk0
gpt remove -i 2 /dev/disk0 #remove the second partition
gpt add -b StartBlock -s NumberOfBlocks -i 2 -t 53746F72-6167-11AA-AA11-00306543ECAC

In your case:

gpt add -b 409640 -s 776617328 -i 2 -t 53746F72-6167-11AA-AA11-00306543ECAC /dev/disk0

Now you should be asked for the FileVault passphrase. Enter it.
Enter exit and quit Terminal
Check the main volume Macintosh HD for errors
Quit Disk Utility and reboot to your main volume

Addendum: Removing the stubborn MBR

You can either use fdisk or gpt to remove the MBR at block 0. If you use an admin user prepend sudo using the gpt .... commands.

First get an overview again. This step is important before you destroy the gpt, because it's the source to rebuild it from scratch:
```
gpt -r show /dev/disk0
```

Then delete the gpt:

diskutil unmountDisk /dev/disk0
gpt destroy /dev/disk0

Create a new GUID partition table:
```
gpt create -f /dev/disk0
```
Finally add all partitions one by one:
```
gpt add -b 40 -s 409600 -i 1 -t C12A7328-F81F-11D2-BA4B-00A0C93EC93B /dev/disk0
gpt add -b 777026968 -s 1269760 -i 3 -t 426F6F74-0000-11AA-AA11-00306543ECAC /dev/disk0
gpt add -b 409640 -s 776617328 -i 2 -t 53746F72-6167-11AA-AA11-00306543ECAC /dev/disk0
```
Hint: You may add and remove partitions in an arbitrary order if you keep the right index number. In the above commands I added the third partition (... -i 3 ...) before adding the second partition (... -i 2 ...). You don't have to unmount disk0 then because the partitions i=1 and i=3 don't contain auto-mounted volumes while the second partition does.

I missed to detect the wrong partition type of your Recovery HD (the third partition with the index number 3) in the first part of my answer. Therefore I used:
```
gpt add -b 777026968 -s 1269760 -i 3 -t 426F6F74-0000-11AA-AA11-00306543ECAC /dev/disk0
```
above instead of the wrong
```
gpt add -b 777026968 -s 1269760 -i 3 -t 48465300-0000-11AA-AA11-00306543ECAC /dev/disk0 #wrong partition type of the Recovery HD
```
to re-add it.

If you still get errors, tackle the MBR with fdisk. If you use an admin user prepend sudo using the fdisk ... commands.:
```
fdisk -i -a hfs /dev/disk0
```
and add the gpt entries with gpt ... outlined above.

Resizing the main volume to fill the whole disk

Finally you probably want to resize the main volume to fill the whole disk.

Get an overview with:
```
diskutil cs list
```
You may have several CoreStorage Logical Volume Groups, if you boot from an external drive with a full system! Use the proper one!
Resize the whole stack:
```
diskutil cs resizeStack lvUUID size #lvUUID is the UUID of the Logical Volume. Usually it's the last one listed.
```
Booted to Yosemite you can use 0g for the size to expand it. 0g is a "magical" size here.
```
diskutil cs resizeStack lvUUID 0g
```
Booted to El Capitan you have to use a real size like 500g. If you get an error use a slightly smaller size like 499g or499500m.
```
diskutil cs resizeStack lvUUID 500g
```

Related Solutions

EFI Partition – Fixing The Broken EFI in macOS

You can recreate the EFI System Partition (ESP) using the command-line gpt tool. It should start at sector 40, and it should be 409600 sectors (exactly 200MiB) long. The GPT entry's type should be C12A7328-F81F-11D2-BA4B-00A0C93EC93B, and if you have a hybrid MBR, the type there should be EE. The format is actually a subset of FAT, not HFS+. You can read the GPT using the command sudo gpt -r show disk0 in a Terminal window, this produces output that looks something like this:

      start       size  index  contents
          0          1         PMBR
          1          1         Pri GPT header
          2         32         Pri GPT table
         34          6         
         40     409600      1  GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B
     409640  447801712      2  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
  448211352    1269536      3  GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
  449480888   40753831         
  490234719         32         Sec GPT table
  490234751          1         Sec GPT header

You can see the correct EFI partition at index 1. If that line doesn't match exactly, the easiest way is to delete the partition in its place and recreate it.

Make sure you know what you're doing before proceeding from here - you may lose data if you mess up.

You can't edit the partition table using gpt while partitions on the drive are mounted, so you'll need to boot from another drive (e.g. a USB stick with the OSX installer) or run the mac in target disk mode and do the partitioning from another mac. You may need to unmount any automatically mounted volumes using diskutil unmountDisk disk0 before proceeding, and in between commands.

To delete your "bad" EFI partition, run this command:

sudo gpt remove -i 1 disk0

Make sure disk0 is really the disk you want to change - the numbers can change between reboots. Also, this will only work if you already have a non-ESP partition in the place of the ESP - if not, deleting partition 1 could be disastrous! In this case, you'll need to move the indices along, as I think the ESP must have index 1. By the sound of it, this won't be necessary in your case.

Once deleted, re-add the partition with the correct layout and type:

sudo gpt add -b 40 -i 1 -s 409600 -t C12A7328-F81F-11D2-BA4B-00A0C93EC93B disk0

This should sort out the partition itself, but as you've created an HFS partition in its place, you need to fix its format as well.

The format of the EFI System Partition is documented by Apple here. As you can see, they recommend you clone an existing ESP rather than recreating the file system with newfs_msdos. If you have an external drive with a GPT partition table (OSX install stick should have it), you can clone that.

Make sure you have your disk and partition numbers the right way around or you may overwrite data:

If disk1 is your external drive, and it contains an ESP as the first partition (disk1s1) and disk0 is the drive whose ESP (disk0s1) you want to fix, run this command:

sudo dd if=/dev/disk1s1 of=/dev/disk0s1

This will copy every single block of disk1's ESP and overwrite the corresponding block in disk0's ESP with it.

Alternatively, take a gamble with newfs_msdos.

MacOS – How to fix broken GPT, GUID and unmountable and without type volumes

If you have a spare linux box you can try to use SystemRescueCD to mount and possibly recover the data on your Mac (hfs+) partitions.

SystemRescueCD

The SystemRescueCD contains TestDisk which I have used to recover data from Linux, Windows as well as Mac file systems:

TestDisk

I think there is also a TestDisk Mac app you can install and run from a Mac OS computer, so as long as you can mount your bad drive you can use TaskDisk to try to receover the data. But I have not tried this so you might have to test it out first on a dummy drive before working on your real drive.

Best Answer

Related Solutions

EFI Partition – Fixing The Broken EFI in macOS

MacOS – How to fix broken GPT, GUID and unmountable and without type volumes

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