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Issue:

I've been unable to boot into my Windows (Boot Camp) partition, which I haven't accessed in about a year.

No Boot Options with Alt Key: Holding down the Opt during startup does not show any boot options, which normally should include the Boot Camp partition.

Startup Disk Cannot Be Verified: When I attempt to boot up by selecting the Boot Camp as the target startup, the system fails to verify the startup disk.

First Aid on the Boot Camp partition is not available (I expect that's default behavior).

I'm looking for guidance or insights from anyone who has experienced similar issues or knows how to resolve this. Any assistance would be greatly appreciated.

System Details:

  • macOS Ventura 13.6.1
  • MacBook Pro (2019)

Update 1:

I noticed a Startup Security option when rebooting in Recovery Mode, and set it to No Security, which allowed me to skirt the 'cannot verify startup disk error' so I can select Windows Boot Camp drive to login with. However, I get a blue screen that says "Stop code: ACPI_BIOS_ERROR". Do you know how to fix this? Side note: I'm planning to see if there is a way to slightly adjust the partition to see if it remaps it automatically fixing any tables.

Update 2:

Note: In Disk Utility it says "Bootable: No", which I'm not sure is standard

In an attempt to address the issue, I followed Repair Bootcamp partition boot entry missing after disk resize.

Now instead of booting into the blue Windows screen, it's a black screen that hangs indefinitely.

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  • 1
    Does the Windows volume appear in the Finder? Oct 28, 2023 at 19:54
  • @DavidAnderson Yes
    – Phillip
    Oct 28, 2023 at 19:55
  • I just now tried doing sudo bless --device /dev/disk0s3 --setBoot --legacy --nextonly but "Legacy mode not supported on this system"
    – Phillip
    Oct 28, 2023 at 20:36
  • 1
    You linked to an article which has the following discrepancies. Updated September 17, 2023 with the opening sentence stating "latest copy of Mac OS X". Well, the latest Mac OS X was Lion (10.7), which was released 12 years ago. The latest macOS is Sonoma (14). According to Apple, no Mac older than a 2017 model is compatible with Sonoma. Oct 30, 2023 at 17:21
  • 1
    The article assumes the Mac is BIOS booting Windows. Starting 2015, Apple removed support for BIOS booting of operating systems. Your Mac can only (U)EFI boot Windows. The images posted in the article are incomplete and/or contain lines of text which are out of order. In the future, I would avoid reading anything this author has published. Oct 30, 2023 at 17:46

1 Answer 1

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I do not feel enough information has been posted in the question to determine the exact problem. My best guess would be to reinstall the Windows boot files. This answer assumes you are UEFI booting Windows 10. I see you have already used the Startup Security Utility to set Secure boot to "No Security". You should also set Allowed Boot Media to "Allow booting from external or removable media".

First you will need to boot from a Windows 10 installation flash drive and then open a Command Prompt window, follow the steps below.

Create a Windows 10 Flash Drive Installer

  1. Download the latest Windows 10 ISO.
  2. ExFAT format a flash drive using the MBR partition scheme.
  3. Mount and copy all the files from the ISO to the flash drive.
  4. Use the Boot Camp Assistant to download the Windows Support Software.
  5. Copy the Windows Support Software to the flash drive.
  6. Boot from the flash drive.
  7. Proceed as if you are installing Windows until asked for a product key.
  8. Press the shift+F10 key combination to open a Command Prompt window.

Rebuild Boot Files

Once you have a Command Prompt window open, enter the following commands.

Mount the EFI volume and assign to drive S:.

mountvol s: /s

Remove any previous backup. If no previous backup exists, then expect error messages to appear.

rd /s /q s:\efi\Microsoft.old
rd /s /q s:\efi\boot.old

Backup existing files by renaming folders. If no previous folders exist, then expect error messages to appear.

ren s:\efi\Microsoft Microsoft.old
ren s:\efi\Boot Boot.old

Determine the existing drive letters. Determine by inspection the drive letter of the main Windows volume. Usually, this is drive C:. If you are using a different drive letter, then make the appropriate substitutions in the subsequent commands.

echo list vol | diskpart

Create new boot files.

bcdboot c:\windows /s s: /f UEFI

Close the Command Prompt window.

exit

Close the remaining windows by clicking on the red box with the white X. The computer should restart.

References

Note: This question is a possible duplicate of Can't boot into Windows 10 after latest updating Mac OS to 10.15.4.

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  • 1
    Quick update (as I'm distant from this issue): I began to suspect that it might have related to not enough space on the Bootcamp partition. In one case, I ended up turning off the hibernation to save space, and I'm not sure if that related to a subsequent boot issue. I haven't installed any Windows 10 updates on my latest test, and have left a good amount of space, and have had no issues yet (requiring a complete reinstall of Bootcamp as before)
    – Phillip
    Nov 11, 2023 at 21:15

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