Level 1

8 points

"Missing Operating System"

I upgraded to High Sierra the other day and noticed my Windows Partition (Win 10) was missing when I held down Alt while starting my MacBook Pro up. I had this problem long ago and created a hybrid MBR to resolve the issue then. Instinctively, I tried again and sure enough, Windows appeared as an option when I turn on the MacBook and hold Alt, but now it says "Missing Operating System." I can boot into Mac OS and Recovery just fine.

I can't see the Bootcamp any longer in Finder, and Disk Utility has it listed as "disk0s4" and it is grayed out. It cannot be mounted or repaired, and it is not an option in Startup Disk.

For convenience sake, attached below is a few commands (diskutil, fdisk, gdisk) from Terminal that are usually requested. I have scoured over the topics on here but I can't seem to crack this.

I'm trying to recover some files that are on the Windows partition, otherwise I would wipe the whole thing and start anew.

Let me know if there's anything to be done - any advice is greatly appreciated.

diskutil list

/dev/disk0 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *750.2 GB disk0

1: EFI EFI 209.7 MB disk0s1

2: Apple_HFS Macintosh HD 549.3 GB disk0s2

3: Apple_Boot Recovery HD 650.0 MB disk0s3

4: Microsoft Basic Data 200.0 GB disk0s4

fdisk: 1> p

Disk: /dev/disk0 geometry: 91201/255/63 [1465149168 sectors]

Offset: 0 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 - 1072844984] HFS+

3: AB 1023 254 63 - 1023 254 63 [1073254624 - 1269536] Darwin Boot

*4: 07 1023 254 63 - 1023 254 63 [1074524160 - 390623232] HPFS/QNX/AUX

sudo gdisk /dev/disk0

Disk /dev/disk0: 1465149168 sectors, 698.6 GiB

Sector size (logical): 512 bytes

Disk identifier (GUID): E3631DF3-C36F-48BA-9F75-769D070772A1

Partition table holds up to 128 entries

Main partition table begins at sector 2 and ends at sector 33

First usable sector is 34, last usable sector is 1465149134

Partitions will be aligned on 8-sector boundaries

Total free space is 1749 sectors (874.5 KiB)

Number Start (sector) End (sector) Size Code Name

1 40 409639 200.0 MiB EF00 EFI System Partition

2 409640 1073254623 511.6 GiB AF00 Customer

3 1073254624 1074524159 619.9 MiB AB00

4 1074524160 1465147391 186.3 GiB 0700 BOOTCAMP

Posted on Feb 17, 2018 5:36 PM

Similar questions

58 replies

Loner T

Level 9

59,536 points

Feb 20, 2018 4:37 AM in response to Birdman688

Answer as 'N' and continue.

Loner T

Level 9

59,536 points

Feb 28, 2018 3:31 AM in response to Birdman688

Do you want to consider removing/re-installing Windows, since you have already recovered the files you needed?

Loner T

Level 9

59,536 points

Feb 18, 2018 3:54 PM in response to Birdman688

Birdman688 wrote:

I would love to try and recover the files in this Boot Camp partition, so if losing the local Recovery HD is part of that, I am willing to make any changes you suggest.

Boot into Internet Recovery, and click on Utilities -> Terminal, and run

diskutil unmountDisk disk0

gpt remove -i 4 /dev/disk0

diskutil unmountDisk disk0

gpt remove -i 3 /dev/disk0

diskutil unmountDisk disk0

gpt remove -i 2 /dev/disk0

diskutil unmountDisk disk0

gpt add -i 2 -b 409640 -s 878907352 -t hfs /dev/disk0

diskutil unmountDisk disk0

gpt add -i 3 -b 879316992 -s 585830393 -t windows /dev/disk0

diskutil repairDisk disk0

Now try booting into macOS normally and check if Finder shows your NTFS file system and Windows files.

Loner T

Level 9

59,536 points

Feb 18, 2018 6:12 PM in response to Birdman688

Did you get any errors in the remove commands?

Your current GPT now includes the MBR side

Birdman688 wrote:

409640 1072844984 2 MBR part 175

1073254624 1269536 3 MBR part 171

1074524160 390623232 4 MBR part 7

Your previous GPT is

409640 1072844984 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC

1073254624 1269536 3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

1074524160 390623232 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

Can you post the output of

fdisk /dev/disk0

Loner T

Level 9

59,536 points

Feb 18, 2018 6:52 PM in response to Birdman688

Do you have an external disk which is 64GB or larger on which a fresh copy of High Sierra can be installed?

If yes, then install it, but do not touch the internal disk. Once installed, boot from it and install GPT Fdisk (https://sourceforge.net/projects/gptfdisk/). Also disable SIP from Local Recovery when booted from the external disk's local Recovery HD.

Loner T

Level 9

59,536 points

Feb 19, 2018 9:27 AM in response to Birdman688

Run (do not type text like this)

sudo gdisk /dev/disk0

p (Print)

d (delete)

2 (GPT2)

d (delete)

3 (GPT3)

d (delete)

4 (GPT4)

x (Experts menu)

l (set alignment ...)

1 (... to 1 sector)

n (New)

2 (GPT2)

409640 (Start)

+878907352 (Size. Notice the "+" sign)

AF00 (Apple HFS)

n (New)

3 (GPT2)

879316992 (Start)

+585830393 (Size. Notice the "+" sign)

0700 (Microsoft Basic Data)

p (print)

w (write)

y (Confirm write)

q (quit if necessary)

Reboot from the external disk and check if you can see the Windows partition from the internal disk.

Birdman688 Author

Level 1

8 points

Feb 19, 2018 1:11 PM in response to Loner T

I have followed these steps exactly, here is the documentation:

GPT fdisk (gdisk) version 1.0.3

Partition table scan:

MBR: hybrid

BSD: not present

APM: not present

GPT: present

Found valid GPT with hybrid MBR; using GPT.

Command (? for help): x

Expert command (? for help): p

Disk /dev/disk0: 1465149168 sectors, 698.6 GiB

Sector size (logical): 512 bytes

Disk identifier (GUID): E3631DF3-C36F-48BA-9F75-769D070772A1

Partition table holds up to 128 entries

Main partition table begins at sector 2 and ends at sector 33

First usable sector is 34, last usable sector is 1465149134

Partitions will be aligned on 8-sector boundaries

Total free space is 1464739501 sectors (698.4 GiB)

Number Start (sector) End (sector) Size Code Name

1 40 409639 200.0 MiB EF00 EFI System Partition

2 409640 1073254623 511.6 GiB FFFF Customer

3 1073254624 1074524159 619.9 MiB FFFF

4 1074524160 1465147391 186.3 GiB FFFF BOOTCAMP

Expert command (? for help): o

Disk size is 1465149168 sectors (698.6 GiB)

MBR disk identifier: 0x00000000

MBR partitions:

Number Boot Start Sector End Sector Status Code

1 1 409639 primary 0xEE

2 409640 1073254623 primary 0xAF

3 1073254624 1074524159 primary 0xAB

4 * 1074524160 1465147391 primary 0x07

Expert command (? for help): n

Expert command (? for help): o

Disk size is 1465149168 sectors (698.6 GiB)

MBR disk identifier: 0x00000000

MBR partitions:

Number Boot Start Sector End Sector Status Code

1 1 1465149167 primary 0xEE

Expert command (? for help): p

Disk /dev/disk0: 1465149168 sectors, 698.6 GiB

Sector size (logical): 512 bytes

Disk identifier (GUID): E3631DF3-C36F-48BA-9F75-769D070772A1

Partition table holds up to 128 entries

Main partition table begins at sector 2 and ends at sector 33

First usable sector is 34, last usable sector is 1465149134

Partitions will be aligned on 8-sector boundaries

Total free space is 1464739501 sectors (698.4 GiB)

Number Start (sector) End (sector) Size Code Name

1 40 409639 200.0 MiB EF00 EFI System Partition

2 409640 1073254623 511.6 GiB FFFF Customer

3 1073254624 1074524159 619.9 MiB FFFF

4 1074524160 1465147391 186.3 GiB FFFF BOOTCAMP

Expert 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/disk0.

Warning: The kernel may continue to use old or deleted partitions.

You should reboot or remove the drive.

The operation has completed successfully.

diskutil unmountDisk disk0

Unmount of all volumes on disk0 was successful

diskutil list

/dev/disk0 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *750.2 GB disk0

1: EFI EFI 209.7 MB disk0s1

/dev/disk1 (external, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *500.1 GB disk1

1: EFI EFI 209.7 MB disk1s1

2: Apple_HFS OS X 499.2 GB disk1s2

3: Apple_Boot Recovery HD 650.0 MB disk1s3

If this looks correct and you would like me to try the previous commands again (with the deleting partitions and sector alignments), let me know! Thanks.

Loner T

Level 9

59,536 points

Feb 19, 2018 2:10 PM in response to Birdman688

We stole space from Macintosh HD, so that the NTFS header would start at the proper start address shown by Testdisk. Does the NTFS partition show files in Finder?

Can you run

diskutil repairDisk disk0

again and see if repairDisk will correct it?

Loner T

Level 9

59,536 points

Feb 19, 2018 5:12 PM in response to Birdman688

Can you go back to the previous entry named BOOTCAMP and check the status at the bottom of the page? Do not use 'p' yet. We should check if Testdisk finds the files using a backup file system header or the header at the beginning of the entry?

Loner T

Level 9

59,536 points

Feb 19, 2018 7:49 PM in response to Birdman688

Since there is no MBR on your internal disk, Fusion may have issues seeing the volume. We should recreate the MBR and test first if Finder can see the Windows volume. The GPT entry should be sufficient, but the missing NTFS header is a problem.

You will need to use the link I posted and recreate the MBR using the Rebuild MBR section, but use only 2 3 instead of 2 3 4 as partitions to be hybridized.

Loner T

Level 9

59,536 points

Feb 20, 2018 11:45 AM in response to Birdman688

If you do not have Windows on the MBA, then you will need to install a new copy, which is a bit of work.

It may be easier to install a VM copy of W10 and then try to run chkdsk on the internal disk's NTFS partition. The unknown is whether the VM copy can see the NTFS partition, that Fusion could not.

Loner T

Level 9

59,536 points

Feb 17, 2018 5:42 PM in response to Birdman688

Post the output of

sudo gpt -vv -r show /dev/disk0

sudo dd if=/dev/rdisk0s4 count=1 2>/dev/null | hexdump -C

Loner T

Level 9

59,536 points

Feb 19, 2018 1:56 PM in response to Birdman688

Good to see the two partitions added. Type 'y' and continue. The EFI partition is rebuilt if it is corrupted.

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"Missing Operating System"