Q: "Missing operating system" after Yosemite upgrade / MBR repair

Question

picturevalve

Level 1 (0 points)

Q: "Missing operating system" after Yosemite upgrade / MBR repair

Yesterday I upgraded my Macbook Pro to Yosemite and my Windows 7 Bootcamp vanished i.e. I couldn't see it from the ALT startup options.

In Disk Utility I can see it named as disk0s4.

I followed the steps here to change the Master Boot Record - now I can see Windows as a startup option, but when I select it I see a "missing operating system" message.

From similar questions on here, here's the output from a few disk commands:

MacBook Pro, OS X Yosemite (10.10.4)

Posted on Jul 6, 2015 3:00 AM

I have this question too

Solved

Loner T

Level 7 (24,825 points)

Safari

A:

Use the Gdisk steps in the linked thread after you substitute your specific start (231436288) in step 7 and size (258797561) in steps 8, and then rebuild your MBR and test. In most cases, the size is typically the sum of the gap and GPT4, which in your case is 61535384 + 197263360 = 258798744 which leaves a gap of 1183 sectors. Small gap for sector alignment is fine.

Posted on Jul 6, 2015 5:25 AM

Q: "Missing operating system" after Yosemite upgrade / MBR repair

All replies

Helpful answers

by picturevalve,

picturevalve Jul 6, 2015 3:34 AM in response to picturevalve
Level 1 (0 points)

Jul 6, 2015 3:34 AM in response to picturevalve
Reply options

Link to this post

by Loner T,

Loner T Jul 6, 2015 4:20 AM in response to picturevalve
Level 7 (24,825 points)

Safari

Jul 6, 2015 4:20 AM in response to picturevalve

The gap between GPT3 and GPT4 indicates a lost NTFS header. Can you use Windows 7 Vanished after Yosemite update... help? as a reference and get started with Testdisk?
Reply options

Link to this post

by picturevalve,

picturevalve Jul 6, 2015 4:49 AM in response to Loner T
Level 1 (0 points)

Jul 6, 2015 4:49 AM in response to Loner T

Loner T! I was hoping you'd show up

I've included screenshots from Testdisk below - I've never used it before, so including a few so you can see what I'm doing.

Thanks!
Reply options

Link to this post

by Loner T,

Loner T Jul 6, 2015 5:05 AM in response to picturevalve
Level 7 (24,825 points)

Safari

Jul 6, 2015 5:05 AM in response to picturevalve

Can you scroll down a bit or increase the size of your Testdisk Terminal window? Seeing the System Volume Information is a very good barometer of this being the correct partition. It should look similar to the following.
Reply options

Link to this post

by picturevalve,

picturevalve Jul 6, 2015 5:10 AM in response to Loner T
Level 1 (0 points)

Jul 6, 2015 5:10 AM in response to Loner T

Yes, the first MS Data has System Volume Information folder.

If I do P: list files on the second MS Data it says "Can't open filesystem. Filesystem seems damaged"
Reply options

Link to this post

by picturevalve,

picturevalve Jul 6, 2015 5:40 AM in response to Loner T
Level 1 (0 points)

Jul 6, 2015 5:40 AM in response to Loner T

Thanks - I've rebuilt GPT4. Before I rebuild the MBR - should I set the boot flag to Y on another other partition as well as 4? I still want to be able to boot into OSX.
Reply options

Link to this post

by Loner T,

Loner T Jul 6, 2015 5:53 AM in response to picturevalve
Level 7 (24,825 points)

Safari

Jul 6, 2015 5:53 AM in response to picturevalve

MBR Boot flag is valid only for Windows. OSX uses GPT and EFI Boot.
Reply options

Link to this post

by picturevalve,

picturevalve Jul 6, 2015 6:08 AM in response to Loner T
Level 1 (0 points)

Jul 6, 2015 6:08 AM in response to Loner T

Getting closer!

I can see Bootcamp in Finder and see all files in the volume.

I can't, however, boot into Windows - it says "the boot selection failed because a required device is inaccessible". A quick look around suggests the Windows Boot Configuration Data Store neesd to be updated with the new partition location, which involves getting the Windows 7 installation disk / USB and choosing "Repair your Computer"

I suppose I should try that?
Reply options

Link to this post

by Loner T,Helpful

Loner T Jul 6, 2015 6:37 AM in response to picturevalve
Level 7 (24,825 points)

Safari

Jul 6, 2015 6:37 AM in response to picturevalve

Please see https://support.microsoft.com/en-us/kb/927392?wa=wsignin1.0 for using it to rebuild BCD. The OS X/Mac side is fine now.
Reply options

Link to this post

by picturevalve,Helpful

picturevalve Jul 6, 2015 6:57 AM in response to Loner T
Level 1 (0 points)

Jul 6, 2015 6:57 AM in response to Loner T

Thank you so much for your help - my issue has been fixed!
Reply options

Link to this post

by Loner T,

Loner T Jul 6, 2015 7:37 AM in response to picturevalve
Level 7 (24,825 points)

Safari

Jul 6, 2015 7:37 AM in response to picturevalve

Glad to see it working. .

Please backup OSX and Windows to two separate external disks formatted appropriately and use these a baseline for future restores.
Reply options

Link to this post

Accepted Answer · Jul 6, 2015 5:25 AM

Loner T

Level 7 (24,825 points)

Safari

Jul 6, 2015 5:25 AM in response to picturevalve

Use the Gdisk steps in the linked thread after you substitute your specific start (231436288) in step 7 and size (258797561) in steps 8, and then rebuild your MBR and test. In most cases, the size is typically the sum of the gap and GPT4, which in your case is 61535384 + 197263360 = 258798744 which leaves a gap of 1183 sectors. Small gap for sector alignment is fine.

Q: "Missing operating system" after Yosemite upgrade / MBR repair

All replies Helpful answers

by picturevalve,

by Loner T,

by picturevalve,

by Loner T,

by picturevalve,

by Loner T,Solvedanswer

by picturevalve,

by Loner T,

by picturevalve,

by Loner T,★Helpful

by picturevalve,★Helpful

by Loner T,

All replies

Helpful answers

by Loner T,Helpful

by picturevalve,Helpful