Windows – How to convert a drive from the GPT format to the hybrid GPT/MBR format when using High Sierra (macOS 10.13.2)

bootbootcamppartitionwindows

Previous versons of OS X and macOS automatically converted pure GPT drives to hybrid GPT/MBR format when the 2nd, 3rd, and/or 4th GPT partitions were formatted "MS DOS (FAT)" by the Disk Utility application or the diskutil command. I am not sure when this changed, but this no longer happens under High Sierra (macOS 10.13.2).

My Mac needs the hybrid format in order to BIOS boot the installed Windows operating system.

What is a procedure to manually convert the drive back to the hybrid format?

Below is the output from the command diskutil list disk0.

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.0 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                 Apple_APFS Container disk1         249.5 GB   disk0s2
   3:       Microsoft Basic Data BOOTCAMP                200.0 GB   disk0s3
   4:       Microsoft Basic Data COMMON                  50.0 GB    disk0s4
   5:                  Apple_HFS Refind                  200.0 MB   disk0s5

The BOOTCAMP volume is NTFS formatted and the COMMON volume is FAT32 formatted.

Note: The next two commands were executed after starting up from macOS Recovery.

Below is the output from the command gpt -r show /dev/disk0.

      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  487304680      2  GPT part - 7C3457EF-0000-11AA-AA11-00306543ECAC
  487714320        496         
  487714816  390623232      3  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
  878338048       2048         
  878340096   97654784      4  GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
  975994880        696         
  975995576     390616      5  GPT part - 48465300-0000-11AA-AA11-00306543ECAC
  976386192     176315         
  976562507         32         Sec GPT table
  976562539          1         Sec GPT header

Below is the output from the command fdisk /dev/disk0.

Disk: /dev/disk0    geometry: 60788/255/63 [976562540 sectors]
Signature: 0xAA55
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 1: EE 1023 254  63 - 1023 254  63 [         1 -  976562539] <Unknown ID>
 2: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
 3: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
 4: 00    0   0   0 -    0   0   0 [         0 -          0] unused

Best Answer

Here, I assume you are using High Sierra (macOS 10.13.2).

To update the MBR partition table, a mapping of the partition types needs to be known. Below is a table of some commonly found types.

Note: The mapping is not one-to-one.

            Partition Type              MBR ID              UEFI GUID
--------------------------------------  ------  ------------------------------------
Apple Mac OS Extended (HFS+ or JHFS+)     AF    48465300-0000-11AA-AA11-00306543ECAC
Apple Boot (Recovery HD)                  AB    426F6F74-0000-11AA-AA11-00306543ECAC
Apple Core Storage                        AC    53746F72-6167-11AA-AA11-00306543ECAC
Apple File System (APFS)                  AF    7C3457EF-0000-11AA-AA11-00306543ECAC
Extensible Firmware Interface (EFI)       EE    C12A7328-F81F-11D2-BA4B-00A0C93EC93B
Linux Filesystem Data                     83    0FC63DAF-8483-4772-8E79-3D69D8477DE4
Linux Swap                                82    0657FD6D-A4AB-43C4-84E5-0933C84B4F4F
Linux Logical Volume Manager (LVM)        8E    E6D6D379-F507-44C2-A23C-238F2A3DF928
Microsoft File Attribute Table (FAT32)    0C    EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
Microsoft Windows NT (NTFS) or ExFAT      07    EBD0A0A2-B9E5-4433-87C0-68B6B72699C7
Microsoft Windows Recovery Environment    27    DE94BBA4-06D1-4D40-A16A-BFD50179D6AC

Here are the methods involving in editing the MBR table to create a hybrid partitioning scheme.

Method 1: Use the Third Party Tool `gdisk`

While booted to macOS, download and install gdisk.

Note: If you get the popup shown below, then will need to run the Terminal application command shown below before trying to install gdisk.
```
xattr -d com.apple.quarantine ~/Downloads/gdisk-1.0.4.pkg
```
Note: The Terminal application can be found under "Utilities" on the menu bar.
Disable SIP and then boot back to macOS. This will allow you to use the commands gpt, gdisk and fdisk. You also can execute gpt, gdisk and fdisk from macOS Recovery, but this may require you to precede the gdisk command with a path.
The command given below can be used to partially display the information contained in GPT stored on disk0. You will need this information verify the changes made to the MBR table. (See the above question for the output from this command.)
```
gpt -r show /dev/disk0 
```
Enter the command given below.
```
sudo gdisk /dev/disk0
```

Enter the input given below. This input is correct for the drive used as an example in this answer. Your actual input may vary from what is shown.

Note: The control+C key can be pressed at anytime to terminate the gdisk command without saving any changes.

r
h
2 3 4
y
af
n
07
y
07
n
w
y

Note: If you encounter the question shown below, enter the answer n.

Unused partition space(s) found. Use one to protect more partitions? (Y/N):

Below is an example of the output after entering the command and the above input.

GPT fdisk (gdisk) version 1.0.4

Partition table scan:
  MBR: protective
  BSD: not present
  APM: not present
  GPT: present

Found valid GPT with protective MBR; using GPT.

Command (? for help): r

Recovery/transformation command (? for help): h

WARNING! Hybrid MBRs are flaky and dangerous! If you decide not to use one,
just hit the Enter key at the below prompt and your MBR partition table will
be untouched.

Type from one to three GPT partition numbers, separated by spaces, to be
added to the hybrid MBR, in sequence: 2 3 4
Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): y

Creating entry for GPT partition #2 (MBR partition #2)
Enter an MBR hex code (default AF): af
Set the bootable flag? (Y/N): n

Creating entry for GPT partition #3 (MBR partition #3)
Enter an MBR hex code (default 07): 07
Set the bootable flag? (Y/N): y

Creating entry for GPT partition #4 (MBR partition #4)
Enter an MBR hex code (default 07): 07
Set the bootable flag? (Y/N): n

Recovery/transformation command (? for help): w

Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!

Do you want to proceed? (Y/N): y
OK; writing new GUID partition table (GPT) to /dev/disk4.
Warning: The kernel may continue to use old or deleted partitions.
You should reboot or remove the drive.
The operation has completed successfully.

As the above message suggests, it would be a good idea to restart the Mac.

Enter the command given below to verify the changes.

sudo fdisk /dev/disk0

Below is an example of the output after entering the command. Except for the start value of partition 1, the remaining start and size values should match the output from the gpt -r show /dev/disk0 command.

Disk: /dev/disk4    geometry: 60788/255/63 [976562540 sectors]
Signature: 0xAA55
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 1: EE    0   0   2 -   25 127  14 [         1 -     409639] <Unknown ID>
 2: AF   25 127  15 - 1023 254  63 [    409640 -  487304680] HFS+        
*3: 07 1023 254  63 - 1023 254  63 [ 487714816 -  390623232] HPFS/QNX/AUX
 4: 07 1023 254  63 - 1023 254  63 [ 878340096 -   97654784] HPFS/QNX/AUX

Note: The descriptions <Unknown ID>, Xenix BBT and HPFS/QNX/AUX are either wrong and/or outdated.

If desired, enable SIP.

Method 2: Use No Third Party Tools

Unless you disable System Integrity Protection (SIP), the solution given below requires booting to macOS Recovery via the internet, built-in recovery or an USB flash drive macOS installer. Once booted to macOS Recovery, open a Terminal application window.

Note: The Terminal application can be found under "Utilities" on the menu bar.

The command given below can be used to partially display the information contained in GPT stored on disk0. You will need this information when editing the MBR table. (See the above question for the output from this command.)
```
gpt -r show /dev/disk0 
```
The interactive command to edit the MBR partition table is given below. All changes will be not be entered in CHS mode.
```
fdisk -e /dev/disk0
```
Entering this command produced the following output
```
fdisk: could not open MBR file /usr/standalone/i386/boot0: No such file or directory
Enter 'help' for information
fdisk: 1> 
```
Note: The control+C key can be pressed at anytime to terminate the fdisk command without saving any changes.
The only entry, in the initial MBR table, defines a "Protective Partition". This partition needs to be truncated to the end of the first partition in the GPT with the GUID of C12A7328-F81F-11D2-BA4B-00A0C93EC93B. This means the start value should remain 1, but the size value should be reduced to the value start + size - 1. The values use in this equation should be taken from GPT. Below is the resulting output from using the edit command to reduce the size of the first MBR partition.
```
fdisk: 1> edit 1
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 1: EE 1023 254  63 - 1023 254  63 [         1 -  976562539] <Unknown ID>
Partition id ('0' to disable)  [0 - FF]: [EE] (? for help) EE
Do you wish to edit in CHS mode? [n] N
Partition offset [0 - 976562540]: [63] 1
Partition size [1 - 976562539]: [976562539] 409639
fdisk:*1>
```

Next, enter the correct values for partition 2. The command is enter and the id is AF. The start and size values are the same as shown in the GPT. Doing so, results in what is shown below.

fdisk:*1> edit 2
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 2: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
Partition id ('0' to disable)  [0 - FF]: [0] (? for help) AF
Do you wish to edit in CHS mode? [n] N
Partition offset [0 - 976562540]: [409640] 409640
Partition size [1 - 976152900]: [976152900] 487304680
fdisk:*1>

Repeat the previous step to update partitions 3 and 4. This is shown below. The id for partition 3 is 07 and for partition 4 is 0C.

fdisk:*1> edit 3
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 3: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
Partition id ('0' to disable)  [0 - FF]: [0] (? for help) 07
Do you wish to edit in CHS mode? [n] N
Partition offset [0 - 976562540]: [487714320] 487714816
Partition size [1 - 488847724]: [488847724] 390623232
fdisk:*1> edit 4
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 4: 00    0   0   0 -    0   0   0 [         0 -          0] unused      
Partition id ('0' to disable)  [0 - FF]: [0] (? for help) 0C
Do you wish to edit in CHS mode? [n] N
Partition offset [0 - 976562540]: [878338048] 878340096
Partition size [1 - 98222444]: [98222444] 97654784
fdisk:*1>

The next command flags the third partition as bootable. This partition was chosen because this is where the Windows resides.
```
fdisk:*1> flag 3
Partition 3 marked active.
fdisk:*1> 
```

The next command to enter is print. This command displays what the updated MBR table would look like. The result is shown below. You can use the output to verify your changes. Except for the start value of partition 1, the remaining start and size values should match the output from the gpt -r show /dev/disk0 command.

fdisk:*1> print
Disk: /dev/disk0    geometry: 60788/255/63 [976562540 sectors]
Offset: 0   Signature: 0xAA55
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 1: EE    0   0   2 - 1023 254  63 [         1 -     409639] <Unknown ID>
 2: AF 1023 254  63 - 1023 254  63 [    409640 -  487304680] Xenix BBT   
*3: 07 1023 254  63 - 1023 254  63 [ 487714816 -  390623232] HPFS/QNX/AUX
 4: 0C 1023 254  63 - 1023 254  63 [ 878340096 -   97654784] Win95 FAT32L
fdisk:*1>

Note: The descriptions <Unknown ID>, Xenix BBT and HPFS/QNX/AUX are either wrong and/or outdated.

The final command quit writes the table back to the MBR, then quit fdisk. This is shown below.
```
fdisk:*1> quit
Writing current MBR to disk.
Device could not be accessed exclusively.
A reboot will be needed for changes to take effect. OK? [n] Y
```
As the above message suggests, it would be a good idea to restart the Mac.
If desired, enable SIP.

Related Solutions

I think I messed up the Fusion Drive on the 1TB iMac (with BootCamp)

Theoretically everything is fine with your Fusion Drive. Fusion Drives look like this. Disk0 is your SSD with 121 GB and disk1 is your HDD with ~1 TB (~1.121 TB summed up).

The larger parts of your SSD (disk0s2) and your HDD (disk1s2) are pooled to a CoreStorage LVG (Fusion Drive: disk3) with a size of 967.8 GB. The rest is reserved for EFIs, a Recovery HD (alltogether ~1.3 GB) and your old Windows partition - now probably free space (~152 GB).

The logical volume 'Macintosh HD' (967.8 GB) spans disk0s2 and disk1s2. This is the first 'Macintosh HD' in picture 1. The volume 'Macintosh HD' - it's the one visible on the desktop - should ideally also have about 967.8 GB. This is the second 'Macintosh HD' in picture 1.
In fact it has only 852.67 GB (see picture 3).

In the second picture the logical volume 'Macintosh HD' is the first listed in black, the volume 'Macintosh HD' is the second listed in black, the other two 'Macintosh HD's listed in grey are the parts of your SSD and HDD dedicated to the logical volume 'Macintosh HD'.

In my opinion something went wrong after deleting various partitions with the Bootcamp Assistant/Disk Utility or in Windows.

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 Mavericks or Yosemite) or a thumb drive containing a full system (preferably Mavericks or Yosemite).

Now you may either repair CoreStorage or rebuild your Fusion Drive:

'Repair CoreStorage' (not recommended):

First i would try to check the volume 'Macintosh HD' with Disk Utility. If the volume is corrupted consider a reinstall of Mac OS X.
If the volume is ok quit Disk Utility
Open Terminal and enter diskutil unmountDisk /dev/LVIdentifier and both diskutil unmountDisk /dev/DiskContainingApple_CoreStorageIdentifier
In your case: first diskutil unmountDisk /dev/disk3 then diskutil unmountDisk /dev/disk0 and diskutil unmountDisk /dev/disk1
remove the EFI NO NAME partition with gpt remove -i IndexNumberOfEFINoName DiskIdentifier:
gpt remove -i 4 disk1
Remount the CoreStorage disks and then the Logical Volume:
In your case: first diskutil mountDisk /dev/disk0 and diskutil mountDisk /dev/disk1 and then diskutil mount /dev/disk3.

enter gpt -r -vvv show /dev/diskIdentfierOfApple_CoreStorage to get infos of your HDD CoreStorage disk.
In your case: gpt -r -vvv show /dev/disk1
It should look like this:

-bash-3.2# gpt -r -vvv show /dev/disk1
gpt show: /dev/disk1: mediasize=1000204886016; sectorsize=512;         blocks=1953525168
gpt show: /dev/disk1: PMBR at sector 0
gpt show: /dev/disk1: Pri GPT at sector 1
gpt show: /dev/disk1: GPT partition: type=C12A7328-F81F-11D2-BA4B-00A0C93EC93B, start=40, size=409600
gpt show: /dev/disk1: GPT partition: type=53746F72-6167-11AA-AA11-00306543ECAC, start=409640, size=1671210848
gpt show: /dev/disk1: GPT partition: type=426F6F74-0000-11AA-AA11-00306543ECAC, start=1671620488, size=1269760
gpt show: /dev/disk1: Sec GPT at sector 1953525167                               
     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    1671210848      2 GPT part - 53746F72-6167-11AA-AA11-00306543ECAC
1671620488       1269760      3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC
1672890248     280634887
1953525135            32        Sec GPT table
1953525167             1        Sec GPT header

The free space on your HDD has 280634887 blocks. Please calculate the biggest block number dividable through 8. That's 280634880 blocks (á 512 bytes) which equals 143685058560 B or ~143.7 GB. Add the size of your HDD CoreStorage Physical Volume (852666400768 B) The result is 143685058560 B + 852666400768 B = 996351459328 B
Resize your HDD CoreStorage physical volume with diskutil cs resizeDisk HDDPVUUID newsize
In your case: diskutil cs resizeDisk 93892BE8-2B7F-4ABD-A4C3-984495DCD98D 996351459328b
Calculate the maximal size of your CoreStorage Logical Volume in diskutil cs list: (size disk0s2) + (size disk1s2) In your case that's 120988852224 B + 996351459328 B = 1117340311552 B. That should be the size of your refreshed Logical Volume Group.
Resize your Logical Volume with diskutil cs resizeVolume LVUUID LVGSize-128 MB In your case that's diskutil cs resizeVolume D237FFDC-7DA4-41D7-AC13-4CC7E5E8C0A0 1117212311552b. If you get an error (There is not enough free space...) choose a smaller size like 1117148311552b.
Quit Terminal and open Disk Utility.
Check your expanded CoreStorage Volume for errors.
Quit Disk Utility, choose your CS volume as startup disk and restart your Mac

'Rebuild Fusion Drive' (recommended if you have a Time Machine backup)

Booted to Internet Recovery Mode open Utilities → Terminal in the menubar and enter:
diskutil cs list to get the CoreStorage listing.
Copy the Logical Volume UUID, it's the fifth listed.
Now delete the Logical Volume with diskutil cs deleteVolume LVUUID.
In your case: diskutil cs deleteVolume D237FFDC-7DA4-41D7-AC13-4CC7E5E8C0A0.
Copy the Logical Volume Group UUID, it's the first listed in the listing of diskutil cs list.
Then delete the Logical Volume Group with diskutil cs delete LVGUUID.
In your case: diskutil cs delete 1EFE58BC-3613-44C4-86EE-D816F3B66E3E
Enter exit and quit 'Terminal'
Open 'Disk Utility'. Enter 'Ignore' if you are asked to fix the drives.
Choose your SSD and partition it: 1 Partition Mac OS X Extended (Journaled), hit the Options button and choose GUID Partiton table and hit OK and Apply.
Please check that the size is ~121 GB

Example:
Choose your HDD and partition it: 1 Partition Mac OS X Extended (Journaled), hit the Options button and choose GUID Partiton table and hit OK and Apply.
Please check that the size is ~1 TB

Example:
Quit Disk Utility and open Terminal
Enter diskutil list

Example (your disk identifiers and sizes are different of course: Your volume SSD probably has the Identifier disk0s2 and the size 121 GB and your volume HDD probably has the Identifier disk1s2 and the size 1.0 TB):
Enter diskutil cs create "Name" IdentifierSSD IdentifierHDD
In your case probably diskutil cs create "Macintosh HD" disk0s2 disk1s2.

Copy the resulting LVGUUID

Example:
Enter diskutil cs CreateVolume LVGUUID jhfs+ "Macintosh HD" 100%.

Example:
Enter diskutil cs list
Check the size of your Logical Volume. It should have the size ~1.121 TB

Example:
Quit Terminal
Open 'Disk Utility' and check your newly created volume for errors
Quit 'Disk Utility'
Attach your external Time Machine backup drive or check this answer if you use NAS or another network share.
Open 'Restore from Time Machine Backup'
Choose the appropriate Time Machine backup and restore your system
Reboot to your restored system.
Unmount and detach your Time Machine backup drive
Open 'Terminal' and enter 'diskutil list'
Check if your 'Recovery HD' is listed.
If your 'Recovery HD' is missing, usually reinstalling your current system with the latest available system installer (e.g. 'Install OS X Mavericks (10.9.5)' if Mavericks is currently installed) will recreate it without loosing any data. AFAIK Recovery Partition Creator 3.8 will NOT create a Recovery HD on CoreStorage volumes.
After reinstalling the system with the latest available system installer open App Store and install the latest security fixes.

MacOS – Mac Pro keeps rebooting when installing Win7 on Mac Pro using EFI Boot/GPT drive

"Windows 7 x64 (64-bit) will NOT boot natively using UEFI on a Macintosh!"

See source with technical details here: https://darobins.wordpress.com/2009/10/04/native-uefi-windows-7-boot-on-mac-mini/

PS It would have been nice to not only copy and paste my installation guide in your question. That cost me some time to put online. A link or reference as source would have been nice. From the title of my post it could have come to your mind as well, that a WIN8 or WIN10 installation had been the goal, not WIN7...EFI Boot Windows 8.1 or 10 Install on MacPro4,1 / Mac Pro (Early 2009)