"Missing Operating System"

Question

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

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Answer 1

Loner T

Level 9

59,536 points

Feb 17, 2018 5:53 PM in response to Birdman688

This is not a valid NTFS header. Typically there are a couple of hundred sectors between GPT3 and GPT4, and the 1743 sectors at the end also look a bit out of the ordinary.

I suggest you use Testdisk to locate the NTFS header as shown in El Capitan has deleted my bootcamp windows partition .

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Answer 2

Birdman688 Author

Level 1

8 points

Feb 20, 2018 11:49 PM in response to Loner T

I wanted to give a quick update tonight: While waiting for the MBA today, I ran Testdisk again and went into the [BOOTCAMP] partition. From there, I was ABLE to copy all of my files over to the Mac partition (and have since backed them up on an external HD). It took quite a few hours to copy everything over, but it reported that 0 files had failed the transfer.

I'm VERY relieved that it looks as though all of my files transferred over properly (I'll play with it in the next few days).

I can certainly still boot Windows 10 into VMWare and attempt a chkdsk, but at least I have everything backed up, and the partition's accessibility in its current state is no longer a top priority for me.

Loner T, you have ben a huge help, and thank you for bringing to my attention this Testdisk program which seems to have retrieved all the files I needed.

For posterity's sake, I will see if Windows 10 can even run a chkdsk on the partition and report back my findings, but if this is something where I have to erase everything and re-partition (or perhaps start using VMWare instead), I will be okay with that.

Thank you for your time, patience, and dedication to this. It has been a harrowing last few days for me and I truly appreciate you working with me on this.

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Answer 3

Loner T

Level 9

59,536 points

Feb 19, 2018 3:12 PM in response to Birdman688

The start/size values match the screen shot you posted on page 1, but the NTFS header does not show in the output of dd command. We may need to run Testdisk again and try and find the list of partitions, before you ran the 'p' command to get the screen shot.

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Answer 4

Loner T

Level 9

59,536 points

Feb 19, 2018 11:57 AM in response to Birdman688

Let us remove the MBR first. It seems to be confusing GPT FDisk.

sudo gdisk /dev/disk0

x (Experts)

p (Print)

o (Print MBR)

n (New protective MBR)

o (Print MBR)

p (Print)

w (write)

y (Confirm write)

q (Quit, if necessary)

diskutil unmountDisk disk0

diskutil list

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Answer 5

Loner T

Level 9

59,536 points

Feb 19, 2018 6:16 PM in response to Birdman688

If NTFS was found using the backup sector, then you will need to boot from the W10 DVD and run chkdsk and test if it rebuilds the MFTs and then try to mount it. We should not change the GPT yet.

Since your internal macOS installation is also not working, we can only address it after you get your Windows files. One recommendation, if we are able to successfully rebuild W10, then you should invest in Winclone and backup the Windows installation for future restorability, before we try and address the macOS side. If you can backup Windows successfully, we can remove it which will improve the chances of recovering macOS successfully.

Do you have a Time Machine backup of macOS?

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Answer 6

Loner T

Level 9

59,536 points

Feb 19, 2018 2:50 PM in response to Birdman688

Are you able to mount disk0s3 using Disk Utility? Also, post the output of

sudo dd if=/dev/rdisk0s3 count=1 2>/dev/null | hexdump -C

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Answer 7

Loner T

Level 9

59,536 points

Feb 20, 2018 9:41 AM in response to Birdman688

We need to run chkdsk on the NTFS partition using the DVD installer or via Fusion, if that is possible. Do you have another Mac?

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Answer 8

Loner T

Level 9

59,536 points

Feb 21, 2018 4:58 AM in response to Birdman688

Excellent. Can you look at Testdisk's Advanced NTFS Boot and MFT Repair page?

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Answer 9

Loner T

Level 9

59,536 points

Feb 18, 2018 3:08 PM in response to Birdman688

The issue now is that your Windows installation starts at sector 879316992 and is 585830393, which is roughly 292GB. It is not the same as the current entry of 200GB. Was your partition resized? Also, your Apple partition ends at 1072844984 which overlaps the current NTFS partition, which means you will lose your local Recovery HD, if we make any changes.

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Answer 10

Loner T

Level 9

59,536 points

Feb 18, 2018 5:35 PM in response to Birdman688

In Terminal, run

gpt -vv -r show /dev/disk0

Select and Copy (Command+C) the terminal output, quit Terminal, start Safari (Get Help Online) and Paste (Command+V) the output as a reply to this discussion.

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Answer 11

Birdman688 Author

Level 1

8 points

Feb 19, 2018 8:26 PM in response to Loner T

Working on that now, here's what I have so far:

sudo gdisk /dev/disk0

Password:

GPT fdisk (gdisk) version 1.0.3

Warning: Devices opened with shared lock will not have their

partition table automatically reloaded!

Partition table scan:

MBR: protective

BSD: not present

APM: not present

GPT: present

Found valid GPT with protective MBR; using GPT.

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 1756 sectors (878.0 KiB)

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

1 40 409639 200.0 MiB EF00 EFI System Partition

2 409640 879316991 419.1 GiB AF00 Customer

3 879316992 1465147384 279.3 GiB 0700

Command (? for help): r

Recovery/transformation 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

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

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):

Set the bootable flag? (Y/N): n

Creating entry for GPT partition #3 (MBR partition #3)

Enter an MBR hex code (default 07):

Set the bootable flag? (Y/N): y

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

I'm sure the answer is in there, but how should I answer the unused partition space question? Thanks!

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Answer 12

Birdman688 Author

Level 1

8 points

Feb 27, 2018 8:16 PM in response to Loner T

I just wanted to give another update now that I've had the weekend to take a crack at this. I followed along on that page, as well as trying some other Testdisk guides, but I was never able to get an option to repair the partition. I could be missing something but at this point I have not been able to re-initialize the partition in such a way as to access it through the MacBook Pro's boot menu.

As I have been able to recover the data thanks to Testdisk copying all the files to the Mac partition, I'm not nearly as concerned as before, but I did want to let you know that I worked on it this weekend with no success in booting to Windows. If there is anything else you'd like for me to try, I'm totally game.

Let me know but either way you've been a huge help with this situation so thanks again!

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