Boot Camp partition not mounting

I can no longer boot into my Windows 7 Boot Camp partition. I had created a third partition for installing Mountain Lion to test some old software so maybe that's the reason? How do I get back into Win7 Boot Camp?


MacBook Air 13", macOS 10.14

Posted on Dec 13, 2019 10:21 AM

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Posted on Dec 17, 2019 10:39 AM

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: 2 3
  7. Y (Good for GRUB question)
  8. N (part 2 boot flag)
  9. Y (part 3 boot flag make NTFS bootable partition)
  10. O (print current Hybrid MBR)
  11. W (Write the new MBR)
  12. Y (Yes! write the new MBR)
  13. Reboot


Here is sample Q&A for this section. Please notice the Press Enter/Return.


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): Press Enter/Return
Set the bootable flag? (Y/N): N

Creating entry for GPT partition #3 (MBR partition #3)
Enter an MBR hex code (default 07): Press Enter/Return
Set the bootable flag? (Y/N): Y


If you are asked about additional space, say 'N' and continue.


105 replies

Dec 27, 2019 10:41 AM in response to Loner T

My NAS's latest TM backup of MBA2013 is seven months old. I've had the MBA2013 at work away from the NAS so it hasn't had a chance to connect and do TM.


Resuming the TM backup now results in:


Time Machine couldn't complete the backup because FileVault 
was encrypting or decrypting a disk.  Backups will resume once
FileVault finishes.


Not sure how long that will take. Maybe FileVault is what was freezing/delaying the partition merge in Disk Utility as well?


The tax information isn't in the TM backup, it is on the Boot Camp partition. TM doesn't backup up Boot Camp.




Dec 27, 2019 2:10 PM in response to ckahn

ckahn wrote:

Not sure how long that will take. Maybe FileVault is what was freezing/delaying the partition merge in Disk Utility as well?

Yes, it can.

The tax information isn't in the TM backup, it is on the Boot Camp partition. TM doesn't backup up Boot Camp.

Unless Winclone is directed to write to external disks, the backup is local. This is the backup I am referring to. I assume you have Winclone backups also stored on NAS or remotely.


Also, I will usually keep critical information on a non-OS specific file system, which allows me to get to it without a dependency on a specific OS. exFAT is a good choice in quite a few cases and can be accessed by either Windows or macOS and a few U*ix variants.


Dec 28, 2019 7:16 PM in response to ckahn

ckahn wrote:

W10 image restored to 2018 and then SysPrep'd after Boot Camp exhibited these errors. Errors still there after SysPrep-ing. Errors still there after Windows Update. Errors still there if I log in as other user.


SysPrep is run on the 'source' Mac, not the 'target' (destination) Mac. See



for reference.

Yes this is a 13-in model with Touch Bar.

Can you follow the TwoCanoes document and instructions?

Dec 29, 2019 5:46 AM in response to ckahn

So I ran SysPrep on Win10 MBA2013 and imaged & restored that over to MBP2018. Same issue with Boot Camp Installation.


Maybe the MBA2013 Win7 Boot Camp installation needs to be uninstalled before the MBP2018 Win10 Boot Camp installation can take place? Because this dialog came up pointing to the source of the older Boot Camp install. Which was no longer at that path. Copying the files to that path didn't work. Pointing the installer to the new path didn't work. Maybe the old installer only works on the old OS.



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Boot Camp partition not mounting

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