Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

Lost Windows startup after disk partitioning in Mac side!

Hi, I lost my windows boot after creating a new small partition in disk utility. Could someone help me pls?

MacBook Pro with Retina display, OS X Mavericks (10.9.1), i7 4850HQ, 16GB RAM, Geforce 750M

Posted on Feb 10, 2016 12:57 PM

Reply
44 replies

Feb 10, 2016 2:33 PM in response to ledstixx

Can you post the output of the following OSX Terminal commands?


diskutil list

diskutil cs list

sudo gpt -vv -r show /dev/disk0

sudo fdisk /dev/disk0


The "sudo" commands will prompt for your password, and it will not be echoed back. You may also see a warning about improper use of "sudo" and potential data loss due to "abuse" of the command.

Feb 10, 2016 7:31 PM in response to Loner T

Hi Loner T,


I have the same problem as ledstixx. I created a separate FAT32 partition to share files between OS X and Windows 8, but when I tried to start up Windows it wasn't there.


I followed your instructions in Repairing Boot Camp after creating new partition , including disabling System Integrity Protection or whatever it's called, and now I can see the Windows partition when I hold option at startup, but when I try to boot it up it says something along the lines of


"Non-system disk - press any key to reboot"


I'm stuck. Please help?

Feb 11, 2016 4:12 PM in response to ledstixx

Executing the following steps will make you lose visibility to OSX partition from Windows. I assume that you will use the "Shared Disk" to replace such visibility.


A. We need to disable SIP.

1. Boot into Local Recovery (Command+R).

2. Start Utilities -> Terminal.

3. Type csrutil disable in Terminal and press Enter/Return.

4. Type csrutil status.

5. Boot normally, and type csrutil status to confirm that all individual entries are still disabled.


B. Rebuild non-standard MBR.


The following steps are non-standard because there is a third user-visible partition. Typically, there are two such partitions in a normal configuration on a single-disk Mac with OS X and Bootcamp. This is fragile and lack of proper backups can lead to potential data loss. Download GPT Fdisk from http://sourceforge.net/projects/gptfdisk/ and install it on the OS X side. The following steps are executed when booted in OS X. If the "Shared Disk" is converted to Free Space or deleted, these numbers (3 4 5) will change back to (2 3 4).


Rebuild MBR to match the new GPT information thus resetting the Hybrid MBR. Use defaults for other questions (like partition codes). The only values that need modifications are the Boot flags and step 10. Accept all other defaults that Gdisk offers. Please see thesample Q&A as an example. These steps can be repeated if you make a mistake before you get to Step 12, otherwise start from Step 1 for these steps. Step 6 has numbers which are typed with a space between the numbers. Please see the sample Q&A before you execute these steps.

  1. Sudo gdisk /dev/rdisk0
  2. P (Print list of parts)
  3. R (Recover)
  4. O (print current Hybrid MBR)
  5. H (chooses Hybrid)
  6. Partitions numbers to be hybridized: 3 4 5
  7. Y (Good for GRUB question)
  8. N (part 3 boot flag)
  9. N (part 4 boot flag)
  10. Y (part 5 boot flag make NTFS bootable partition)
  11. O (print current Hybrid MBR)
  12. W (Write the new MBR)
  13. Y (Yes! write the new MBR)
  14. Reboot


Here is sample Q&A for this section. Please notice the Press Enter/Return. Accept defaults offered by Gdisk.


Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): Y


Creating entry for GPT partition #3 (MBR partition #2)

Enter an MBR hex code (default AF or AB): Press Enter/Return

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


Creating entry for GPT partition #4 (MBR partition #3)

Enter an MBR hex code (default AB or 0B or 0C): Press Enter/Return

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


Creating entry for GPT partition #5 (MBR partition #4)

Enter an MBR hex code (default 07): Press Enter/Return

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


Feb 11, 2016 4:20 PM in response to Loner T

Aren't there any easy way for going back to normal. The shared disk is nothing, I created it for sharing some files between mac os and windows and still didn't use it. There weren't any warning when I was creating to the extra partition, actually shred partition is not so important for me. The important thing is existing mac and windows disks because I've project files in them.

Lost Windows startup after disk partitioning in Mac side!

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple ID.