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Boot Camp won't start after OSX Yosemite upgrade

Like so many others, I installed OSX Yosemite this morning and now Boot Camp no longer works.


After I updated to Yosemite I restarted my computer, held down alt, and was presented nothing but a Macintosh HD. I followed “Loner T’s” instructions…


ndiskutil list

diskutil cs list

sudo gpt -vv -r show /dev/disk0

sudo fdisk /dev/disk0

Enter you password when prompted.


…and now a windows option is available during startup. However, when selected, all I get is a black screen with "A disk read error occurred" notice.


I’m in serious trouble if I cannot repair this issue. PLEASE HELP.

iMac, OS X Yosemite (10.10), Windows 7

Posted on Oct 18, 2014 12:00 PM

Reply
59 replies

Oct 18, 2014 7:15 PM in response to Baja Tym

After W7 was installed, did you create a System Repair Disk? W7 only allows a CD/DVD to be created for System Repair, and that is what is needed for repair.


If you not have one, if you access to another W7 machine, since it is a commong disk for all of W7, you can build one and use it to repair the Mac Windows installation.

Oct 19, 2014 7:37 AM in response to Loner T

"1. If the 'dd' command shows the "R.NTFS" string, it indicates that the NTFS header is intact. A repair is possible. Since you are using rdisk0s4, it may save you some time.

2. Please post a screen shot of the Testdisk window which shows the files. Is there a file called 'System Volume Information' in that list? Does the start/size shown in the Testdisk window match the following entry?


1752625152 200898560 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7"

User uploaded file

Oct 19, 2014 8:06 AM in response to Loner T

Unless something resolves this soon, I think I'm going to just use TestDisk to copy the files to my Mac partition and then start over. I'm just thankful I'm able to use the tool to recover the files.


Thank you again for all your help. I think its time to let my Windows programs/software go the way of the dinosaur and reinvest in some Mac versions.


Good luck to everyone on their upgrade to Yosemite and their Boot Camp repairs!

Oct 19, 2014 8:26 AM in response to Baja Tym

This is excellent. Is this the first MS Data you have looked at? Can you do a quick look in other MS Data entries? The three numbers after MS Data are start/end/size of this deleted partition.


1. If there are any other partition entries that overlap this start/end/size, then a decision must be made if there is willingness to lose data from this or the other. From your original GPT entries (for GPT#4 and before that) 1118887936 is a bit after 1118887240 (+696 bytes).


1118887240 633737912

1752625152 200898560 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7


2. Yosemite upgrade killed it, which is now fully established.

3. There is a procedure in Bootcamp missing after expanding partition which deletes the current GPT#4, recreates it using what Testdisk found, and then verification validation to make sure everything works. Please take a look at the thread. If you are uncomfortable, I can cut-and-paste the parts you need from there into this thread.

Oct 19, 2014 11:27 AM in response to Baja Tym

1. The goal of the next steps is to move the GPT#4 entry from


1752625152 200898560 4 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7


to


1118887936 834635769


2. Download GPT Fdisk from http://sourceforge.net/projects/gptfdisk/.

3. Run the following commands. Use "?" if you need to see the built-in help.


sudo gdisk /dev/disk0

p

d

4

n

4

(Put the correct Start value here)

(Put the correct End value here)

p

w

y


Now run sudo gpt -vv -r show /dev/disk0 and verify. Reboot.


4. Run the command sudo dd if=/dev/rdisk0s4 count=1 2>/dev/null | hexdump -C and verify that you can see "R.NTFS".


5. In Gdisk, re-create a Hybrid MBR with 2 3 4 (and allow it to add the EFI into the MBR). There is a space between 2 and 3 and 4.


sudo gdisk /dev/disk0

type 'r' for Recovery Transformation Menu

type 'h' for Hybrid MBR


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 4

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 AB):

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


Creating entry for GPT partition #4 (MBR partition #4)

Enter an MBR hex code (default 07):

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


type 'w' to write MBR

type 'y' to confirm the write.


6. Reboot into OS X.

7. Verify that Bootcamp volume is visible in Finder.

8. Verify that you can see files in Bootcamp volume in Finder.

9. Verify that you can select Bootcamp in System Preferences -> Startup Disk.

10. Select Bootcamp and reboot. If you need startup repair, use your Windows installation media.

Oct 19, 2014 12:03 PM in response to Loner T

LonerT,

I appreciate your knowledge and willingness to help out all of the unfortunate souls that have experienced the bootcamp destruction after upgrading. My experience was going from Mountain Lion to Mavericks. I ended up doing the "Nuke and Pave" option. I really don't want to go that direction again. Windows installs can be rather challanging. Especially when you reach the "limit" of times that you are allowed to install after a disk crash etc. I think I saw a post from you stating that Apple may eventually fix the destruction of bootcamp after upgrading to Yosemite in a later update. Is that correct? Regardless, is there a way to upgrade without having to "Nuke and Pave"? How do I keep my windows install in bootcamp? I would like to have all my computers with the latest OS. Thanks.

Oct 19, 2014 1:07 PM in response to Motleymongoose

Motleymongoose wrote:


I really don't want to go that direction again. Windows installs can be rather challanging. Especially when you reach the "limit" of times that you are allowed to install after a disk crash etc. I think I saw a post from you stating that Apple may eventually fix the destruction of bootcamp after upgrading to Yosemite in a later update. Is that correct?

They may, but I am not holding my breath. The current Apple Software update track record is less than stellar, and I am a skeptic.


Regardless, is there a way to upgrade without having to "Nuke and Pave"? How do I keep my windows install in bootcamp? I would like to have all my computers with the latest OS. Thanks.


This is what I would recommend.


1. Check if you are using a traditional Bootcamp windows using sudo fdisk /dev/diskN (where N is your Bootcamp disk). If you see more than one entry (usually four entries), then you are using a Hybrid MBR, if you see a single entry, then it is an EFI installation and is on a pure GPT disk. Your GPT should have at least 4, most likely 5 entries (EFI/ESP, OSX, Recovery HD, MSR, MSD) for an EFI installation. An EFI installation is supported on UEFI models, which are typical late 2013+ Macs.

2. Download Winclone 4.4 from https://twocanoes.zendesk.com/hc/en-us/articles/202758785 . It is probably the best USD29.99 you will spend on a non-Apple product, if you are a Windows user on a Mac.

3. Create a Winclone image of every Bootcamp/Windows installation that you want to run on Yosemite, on a non-Yosemite machine. Make a second copy on an external disk for safekeeping. Winclone supports Finder drag-and-drop to make such copies. Shrink all such images.

4. Use Bootcamp Assistant on the pre-Yosemite machine and remove Bootcamp/Windows.

5. Upgrade to Yosemite.

6. Create a FAT32 partition on Yosemite machine which is about 4-8GB larger than the size of the original Bootcamp/Windows. This is done via Disk Utility (not Bootcamp Assistant). BA does extra work with a Hybrid MBR which conflicts with a Winclone restore.

7. Restore Bootcamp/Windows from step #3 to the now Yosemite machine. Test.

8. Create a thread on the forum, if you run into any issues.

9. I have not seen any reports of Yosemite+EFI Windows running into any issues. All have been Hybrid MBR installations, so far.

Oct 19, 2014 2:32 PM in response to Loner T

OK, so I am new to the apple hardware community. I am trying to upgrade a 2012 MBP. I have one large partitioned hard drive with OS X on one partition and Bootcamp on another. I assume that N=0 because I only have one hard drive. It had four entries. That means I am using a hybrid MBR (Master Boot Record). Winclone cautions to check the disk for errors before creating an image. Disk Utility reports that the EFI installation is error free. This is confusing based on what you said about an EFI installation. I have four entries but and EFI installation? Winclone also suggests to run SysPrep prior to creating the image. Is that in the bootcamp assistant utility? Do I need to perform that step? One of the steps is to create a FAT32 partition. The current Windows partition is NTFS. Is that going to be a problem?

Oct 19, 2014 10:03 PM in response to Baja Tym

I just successfully installed Windows 8.1 Update 1 on BootCamp on Mac OS X Yosemite. Here is a step by step I just wrote, hope it helps y'all:


How to successfully install Windows 8, or above, on Mac OS X Mavericks or above:


Requirements:

1- Windows OS ISO Image file

2- An 8GBs USB Flash Drive

3- A good Internet connection as you will need to download the Windows compatible drivers for your Mac


Steps:

1- Open up Disk Utility and create an additional partition for Windows formatted as ExFat. 100GBs, or above, is recommended as update to the operating system, as well as Apps requiere space on your HD or SSD [This step can be done during Mac OS X's installation process]

2- Open up BootCamp Assistant

3- Make sure only the 'Create a Windows 7 or later version install disk' is checked and your USB Flash Drive plugged in and click 'Continue'

4- Click 'Choose' and select your Windows ISO Image file

5- Select the USB Flash Drive you will be using during the installation process and click continue to confirm

6- Once done, restart your Mac and hold down the 'alt/option' key on your keyboard to bring up the Boot Menu

7- Select the USB Flash Drive named Windows, not the UEFI Boot

8- Install Windows as you normally would

* Remember to press and hold the 'alt/option' key, and select the Windows Partition, whenever the installation process requires your Mac to restart

* http://msdn.microsoft.com/en-us/library/windows/apps/jj945423.aspx

* http://windows.microsoft.com/en-us/windows-8/install-windows-on-mac

Boot Camp won't start after OSX Yosemite upgrade

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