MacOS – Error when installing El Capitan: disk does not use GUID partition scheme, and I am unable to convert

macospartitionupgrade

I am running Yosemite version 10.10.5. I have a second partition running Windows 10. My main partition, running OS X, is formatted as Mac OS Extended (Journaled). I try to follow the instructions in the error message, but the Option button is not available.

I do not know how to proceed, and would appreciate some help.

Terminal output:

diskutil cs list:

No CoreStorage logical volume groups found

sudo gpt -r show /dev/disk0:

gpt show: error: bogus map
gpt show: unable to open device '/dev/disk0': Undefined error: 0

sudo fdisk /dev/disk0:

Disk: /dev/disk0    geometry: 29185/255/63 [468862128 sectors]
Signature: 0xAA55
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 1: AF   25 127  15 - 1023 254  63 [    409640 -  400094952] HFS+        
 2: AB 1023 254  63 - 1023 254  63 [ 400504592 -    1269536] Darwin Boot 
*3: 07 1023 254  63 - 1023 254  63 [ 401785650 -   67071375] HPFS/QNX/AUX
 4: 00    0   0   0 -    0   0   0 [         0 -          0] unused

sudo gdisk /dev/disk0:

sudo: gdisk: command not found

Best Answer

Considering the comments and the results of the different listings above, Yosemite probably was installed with a hack to enable a Windows MBR only install.

I assume it was the Yosemite MBR Patch 10.10 (14A389). The patch allows you to install Yosemite to a disk with a pure MBR partition table and not the default GUID partition table with a pMBR or hybrid MBR (if Windows is installed).

Depending on the efforts needed to save your data, you may either backup everything, reinstall first Yosemite (or El Capitan) from scratch after partitioning the main disk with a GUID partition table and migrate your data from the backup and then install Windows with Boot Camp Assistant or create a GUID partition table with proper partition values manually after booting to Internet Recovery Mode. The latter will probably render Windows unbootable.

Since the first method is trivial I only describe the second one.

Add a GUID partition table manually:

This method will probably render Windows unbootable!

Preparation:

Backup your data - especially any data on your Windows partition.
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 to 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 (Mavericks or Yosemite) or a thumb drive containing a full system (Mavericks or Yosemite).

Adding GUID partition table and the already existing MBR partitions:

Open Utilities -> Terminal
Enter diskutil list to get an overview
Unmount your main disk with diskutil umountDisk /dev/disk0 (assumimg disk0 is the disk identifier of your main disk).
Add an GUID partition table with gpt create /dev/disk0

Add the EFI and the existent "MBR partitions":

The command basically looks like this:

gpt add -b StartBlock -i IndexNumber -s NumberOfBlocks -t Type device

To add all your partitions enter with the data found in your fdisk list:

gpt add -b 40 -i 1 -s 409600 -t C12A7328-F81F-11D2-BA4B-00A0C93EC93B /dev/disk0
gpt add -b 409640 -i 2 -s 400094952 -t 48465300-0000-11AA-AA11-00306543ECAC /dev/disk0
diskutil umountDisk /dev/disk0
gpt add -b 400504592 -i 3 -s 1269536 -t 426F6F74-0000-11AA-AA11-00306543ECAC /dev/disk0
diskutil umountDisk /dev/disk0
gpt add -b 401785650 -i 4 -s 67071375 -t EBD0A0A2-B9E5-4433-87C0-68B6B72699C7 /dev/disk0

The size of the last partition (your Windows partition) is odd because usually it's a multiple of 8. But I have no explication for this.

The first partition is the EFI partition, the second your main Yosemite volume, the third volume is your Recovery HD and the last one is the Windows partition.

You may label your partitions with following command if they have no names:

gpt label -i number -l name device

Example:

gpt label -i 2 -l "Macintosh HD" /dev/disk0s2

Quit Terminal by entering quit and start Disk Utility
Check the consistency of your main volume (disk0s2)
Reboot to your main volume and install El Capitan

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 – Different partition configuration between gpt and fdisk

Update 1

This step will involve configuring Master Boot Record (MBR) of your physical internal drive. The MBR is stored on the first 512 bytes of this drive. This space is shared by boot code and the MBR partition table.

This step can not be preformed under OS X 10.11 (El Capitan) with System Integrity Protection (SIP) turn on. (This is the default setting.) If you are using OS X 10.11, you must disable SIP, complete this step, then restore SIP. See the link: How do I disable System Integrity Protection (SIP) AKA “rootless” on OS X 10.11, El Capitan?.

In a Terminal application window, enter the following commands. The first fdisk command flags the Windows partition as the active partition. The second fdisk command changes the Windows partition id to 7.

INPUT=$(printf  "f  4\nq\ny")
sudo  fdisk  -e  /dev/disk0  <<<"$INPUT"  &>/dev/null
INPUT=$(printf  "s  4\n7\nq\ny")
sudo  fdisk  -e  /dev/disk0  <<<"$INPUT"  &>/dev/null

You may need to restart your computer after completing this step.

Original Answer

The command fdisk displays the contents of the Master Boot Record (MBR) partition table. This table can only contain 4 entries and is stored at address 0 of your disk. The command gpt displays the contents of the GUID partition table (GPT). This table can contain 120 entries and starts at address 1 of your disk. (A backup GPT is also stored at the end of the disk.) Legacy systems use a MBR scheme while more modern computers use a GPT scheme. Normally, OS X uses a GPT scheme. When the GPT is employed, the MBR table still exists, but is now called a Protective Master Boot Record (PMBR) table. This PMBR table contains a single entry with ID of EE. This fools any legacy applications, that only use a MBR scheme, into seeing the disk as occupied by a single partition.

Older Mac computers install Windows using the MBR scheme. It is my understanding this is also a requirement for Windows 7 installations. To accommodate both schemes simultaneously, Apple shrinks the EE partition in the MBR table to end at the same location as the first partition in the GPT. Usually, the next three partitions in the GPT match the last three partitions in the MBR table.

Anyway, as far as I can tell, if you enter the command given below in a Terminal application windows, your partitions should be fixed.

sudo diskutil eraseVolume "Free Space" name /dev/disk0s4

While the above command should fix the partitioning, the 4th partition in the MBR partition table will not be marked as "active". So if you still can not boot to Windows, let me know and I will include steps to mark this partition as "active".