MacOS – Partition type for boot drive FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF and more

bootcampmacospartition

I was trying to install Ubuntu onto my MacBook Pro 2011 (Catalina running via Catalina Patcher) which already had Windows 10 with bootcamp. When I tried to run Windows again, I couldn't so I decided to delete Windows 10 and Ubuntu and just keep MacOS. I deleted the partitions but couldn't get the deleted space to combine with the MacOS partition. When I checked the type, it said unknown type. So I rebooted my computer but when it turned on it started flashing the question mark file. I found a previous question that matched my problem so I followed it.

Data Not Backed Up, Partition Type: FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF

I got to the step where you do gpt remove then I realized I needed my original numbers to be able to do gpt add. Is there any way I can get my boot, data and settings back?

Partition removed

This is my first time posting, I usually read other questions and the answers a few times over but this time I really messed up. Any and all help is very much appreciated. Thank you in advance.

TLDR: Forgot to note down the size and starting before gpt remove.

output from the commands export LC_CTYPE="ASCII";dd if=/dev/disk1 count=1 skip=409640 | vis -c

enter image description here

After running the gpt command that @David Anderson said below. I was able to boot using an external drive and see my MacOS partition. I restarted and was able to boot into my original drive. The only problem is that there seems to be 187.85GB of memory available rather than the full 240GB.

Edit: I was able to remove the "free space" partition from Disk Utility and now have access to all 240GB.

Thank you so much @David Anderson, you saved 4 years worth of my data and settings.

Best Answer

Note: This answer assumes the missing partition on disk1 was not part of a fusion container.

The answer you posted shows the string NXSB\0\^P\0\0+\M-L\M-;\^B\0\0\0\0. This can be converted to hexadecimal and ASCII values by entering the commands given below.

export LC_CTYPE="ASCII"
echo -nE "NXSB\0\^P\0\0+\M-L\M-;\^B\0\0\0\0" | unvis | hexdump -Cv

The output from this command is given below.

00000000  4e 58 53 42 00 10 00 00  2b cc bb 02 00 00 00 00  |NXSB....+.......|
00000010

The string 2b cc bb 02 00 00 00 00 when byte reversed is the hexadecimal value of 2bbcc2b, which is 45,861,931 in decimal. This means the APFS file system contains 45,861,931 blocks, where a block is 4096 bytes in size. In your case, this can be converted to 512 byte sectors by multiplying by 8. The result is 366,895,448 sectors. In this case, the commands to add the APFS container partition are given below.

diskutil unmountdisk disk1
gpt add -i 2 -b 409640 -s 366895448 -t 7C3457EF-0000-11AA-AA11-00306543ECAC /dev/disk1

Note: If missing partition is part of a fusion container, then the value of 366895448 needs to be reduced by the byte size of the other partition after dividing by 512.

Related Solutions

MacOS partition startup Volume type FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF

The proper GUID of APFS partitions is 7C3457EF-0000-11AA-AA11-00306543ECAC.

The default pMBR was replaced with an old-style MBR, probably by the Linux installation!

Your boot system (in Internet Recovery Mode) seems pretty old. Any disk or partition verification executed with diskutil may yield some bogus result. In no case try to repair anything with diskutil!

To get your APFS partition back remove partition disk0s2 and restore it with the proper type:

Open in the menubar > Utilities > Terminal

get some details:

diskutil list #below I assume the disk identifier of the internal disk is disk0
gpt -r show disk0

Unmount disk0:
```
diskutil umountDisk disk0
```

remove and restore the 2nd partition:

gpt remove -i 2 disk0
diskutil umountDisk disk0
gpt add -i 2 -b 409640 -s 372637568 -t 7C3457EF-0000-11AA-AA11-00306543ECAC disk0

verify disk and partition:

diskutil list
diskutil verifyDisk disk0       
diskutil verifyVolume disk0s2

Your Mac should be able to boot despite the MBR.

If you want (or have) to restore the pMBR because the MBR is stubborn/blocks the modification of the partition table do the following:

get all disk details:

diskutil list #below I assume the disk identifier of the internal disk is disk0
gpt -r show disk0

replace the GUID partition table:

diskutil umountDisk disk0
gpt destroy disk0
gpt create -f disk0

re-add all previous partitions visible in the last gpt -r show disk0 output:

gpt add -i 1 -b 40 -s 409600 -t C12A7328-F81F-11D2-BA4B-00A0C93EC93B disk0
gpt add -i 2 -b 409640 -s 372637568 -t 7C3457EF-0000-11AA-AA11-00306543ECAC disk0
gpt add -i 3 -b 373047208 -s 262144 -t 426F6F74-0000-11AA-AA11-00306543ECAC disk0
gpt add -i 4 ...
gpt add -i 5 ...

If you get a resource busy error after one of the steps, just unmount disk0 again with

diskutil umountDisk /dev/disk0

Finally verify disk and partitions:

diskutil list
diskutil verifyDisk disk0       
diskutil verifyVolume disk0s1
diskutil verifyVolume disk0s2
diskutil verifyVolume disk0s3
#disk0s4 & disk0s5 can't be verified with the default macOS tools because the latter is a Linux swap and the former a Linux partition, probably with ext4

MacOS – FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF partition type for primary partition

Note: This answer assumes the Mac only has one internal drive.

Follow the steps given below.

Determine the partition offset and disk size in blocks. To do this, enter the command given below in a Terminal application window.
```
diskutil info disk0s2 | grep -e Offset -e Size
```
Below is an example output where the block size is 512 bytes. From the output, the partition offset and disk size can be determined as 409640 blocks and 195312500 blocks, respectively.
```
   Partition Offset:         209735680 Bytes (409640 512-Byte-Device-Blocks)
   Disk Size:                175.8 GB (175790436352 Bytes) (exactly 343340696 512-Byte-Units)
   Device Block Size:        512 Bytes
```
Below is an example output where the block size is 4096 bytes. From the output, the partition offset can be determined as 76806 blocks. To get the disk size in 4096 bytes blocks, the value of 390625232 512-Byte-Units needs to be divided by 8 to get 48828154 blocks.
```
   Partition Offset:          314597376 Bytes (76806 4096-Byte-Device-Blocks)
   Disk Size:                 200.0 GB (200000118784 Bytes) (exactly 390625232 512-Byte-Units)
   Device Block Size:         4096 Bytes
```
Use the key combination Option-⌘-R to boot to macOS Recovery over the Internet.

Enter the commands below in a Terminal application window. Here, you will need to replace <offset-in-blocks> and <size-in-blocks> with an actually numbers.

Disk=$(diskutil list | grep "(internal, physical)")
Disk=${Disk/ *}
gpt -f remove -i 2 $Disk
gpt -f add -i 2 -b <offset-in-blocks> -s <size-in-blocks> -t apfs $Disk

For example, if you used the output from the first example in step 1, then you would enter the commands given below.

Note: The commands are case-sensitive.

Disk=$(diskutil list | grep "(internal, physical)")
Disk=${Disk/ *}
gpt -f remove -i 2 $Disk
gpt -f add -i 2 -b 409640 -s 343340696 -t apfs $Disk

Note: Below is the legacy version of the above commands. You can use these commands, if the above two commands generate an illegal option error message.

Disk=$(diskutil list | grep "(internal, physical)")
Disk=${Disk/ *}
diskutil unmountdisk $Disk
gpt remove -i 2 $Disk
diskutil unmountdisk $Disk
gpt add -i 2 -b <offset-in-blocks> -s <size-in-blocks> -t 7C3457EF-0000-11AA-AA11-00306543ECAC $Disk

Boot back to macOS.
Enter the command given below to recover the free space.
```
sudo diskutil apfs resizeContainer disk0s2 0
```