Bootcamp - Missing Operating System

Question

Level 1

4 points

Bootcamp - Missing Operating System

Product: Retina MacBook Pro 2012

OS: Sierra

Hello,

Today when I tried to boot into my Bootcamp Partition (Win 10) it failed and said that the operating system was missing. I have no idea what has caused this issue as I haven't done any significant changes to either partitions for months and it was working fine yesterday. The disk is still reachable on the OSX side and seems to be completely intact (I can read files perfectly fine) and Disk Utility cannot find any disk errors. However, the partition still will not boot. Does anyone know how to fix this issue?

Many thanks,

MacBook Pro with Retina display

Posted on Jan 17, 2017 9:27 AM

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Answer 1

Loner T

Level 9

59,536 points

Jan 17, 2017 12:38 PM in response to gb9876

Your MBR (Fdisk output) is incorrect. Can you use El Capitan has deleted my bootcamp windows partition as a reference and download GPT Fdisk and use the second set of Gdisk steps to rebuild the MBR. Please test after MBR is rebuilt.

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Answer 2

Loner T

Level 9

59,536 points

Jan 17, 2017 9:59 AM in response to gb9876

From OSX Terminal, please post the output of

diskutil list

diskutil cs list

sudo gpt -vv -r show /dev/disk0

sudo fdisk /dev/disk0

The 'sudo' command will prompt you for your password, which will not be echoed back you.

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Answer 3

gb9876 Author

Level 1

4 points

Jan 17, 2017 9:52 AM in response to Loner T

Many Thanks for you're prompt reply. Here is the information you requested.

Diskutil List:

/dev/disk0 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *251.0 GB disk0

1: EFI EFI 209.7 MB disk0s1

2: Apple_HFS Macintosh HD 175.1 GB disk0s2

3: Apple_Boot Recovery HD 650.0 MB disk0s3

4: Microsoft Basic Data BOOTCAMP 75.0 GB disk0s4

diskutil cs list:

No CoreStorage logical volume groups found

sudo gpt -vv -r show /dev/disk0:

gpt show: /dev/disk0: mediasize=251000193024; sectorsize=512; blocks=490234752

gpt show: /dev/disk0: Suspicious MBR at sector 0

gpt show: /dev/disk0: Pri GPT at sector 1

gpt show: /dev/disk0: Sec GPT at sector 490234751

start size index contents

0 1 MBR

1 1 Pri GPT header

2 32 Pri GPT table

34 6

40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B

409640 342071168 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC

342480808 1269536 3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

343750344 312

343750656 146483200 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

490233856 863

490234719 32 Sec GPT table

490234751 1 Sec GPT header

sudo fdisk /dev/disk0:

Disk: /dev/disk0 geometry: 30515/255/63 [490234752 sectors]

Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: EE 1023 254 63 - 1023 254 63 [ 1 - 409639] <Unknown ID>

*2: 07 25 127 15 - 1023 254 63 [ 409640 - 342071168] HPFS/QNX/AUX

3: AB 1023 254 63 - 1023 254 63 [ 342480808 - 1269536] Darwin Boot

4: 0C 1023 254 63 - 1023 254 63 [ 343750656 - 146483200] Win95 FAT32L

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Answer 4

joo2h

Level 1

85 points

Jan 17, 2017 10:37 AM in response to gb9876

That means the OS is just corrupted but the data is still intact. You may have to reinstall Windows again. If I was you I would try a few things things.

1. See if you can boot Windows into SafeMode. When you start up bootcamp see if you see any recovery options at the bottom of the screen. Sometimes you can hit f2-f10 ( Not sure which one ) to get into recovery mode. From this environment you can attempt to restore Windows.

2. Restore a Time Machine backup if you have one from the last few days. This will allow your Mac to go back to the way it was before your issue with bootcamp

3. Backup the data and reinstall Windows. If all else fail this may be your best bet. You will lose any data that is not backed up.

Here are some links you may find helpful

Windows 10 ISO file

https://www.microsoft.com/en-us/software-download/windows10ISO

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Answer 5

Loner T

Level 9

59,536 points

Jan 17, 2017 12:53 PM in response to gb9876

The 'suspicious' MBR is due to the combination of a GPT overlaid with a Hybrid MBR. Normally, GPT disks have a 'Protective' MBR. Here is an example.

sudo gpt -vv -r show /dev/disk0

gpt show: /dev/disk0: mediasize=1000555581440; sectorsize=512; blocks=1954210120

gpt show: /dev/disk0: Suspicious MBR at sector 0

gpt show: /dev/disk0: Pri GPT at sector 1

gpt show: /dev/disk0: Sec GPT at sector 1954210119

start size index contents

0 1 MBR

1 1 Pri GPT header

2 32 Pri GPT table

34 6

40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B

409640 1448624648 2 GPT part - 48465300-0000-11AA-AA11-00306543ECAC

1449034288 1269536 3 GPT part - 426F6F74-0000-11AA-AA11-00306543ECAC

1450303824 1712

1450305536 503904256 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

1954209792 295

1954210087 32 Sec GPT table

1954210119 1 Sec GPT header

Please remember to back up OSX, Windows and create a Windows System Restore point.

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Answer 6

gb9876 Author

Level 1

4 points

Jan 17, 2017 12:38 PM in response to Loner T

You're a star windows now boots successfully! Although, I still have no idea how it got corrupted and sudo still thinks it is a suspicious MBR.

Thanks you very much for all you're help 🙂

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