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I have a MacBook Pro (Retina, 13", Late 2013, 8GB/251GB) on which I have had a Bootcamp partition installed with Windows7 for several years (probably since early days, i.e. since 2014). Initially the MBP ran Mavericks OS, which I thereafter have continuously updated to current OS of High Sierra (10.13.6). Booting Windows has never been a problem. Until now. Now it does not show up when booting and pressing Alt/Option - only the Macintosh HDD is visible.

Half a year ago I did the stupid mistake of running down free HDD space to something like 10 GB and as people might know this is not really appreciated by MacOS. However, I was able to get back to dry land after reading several forum posts. I am suspecting that this episode might have been the event that screwed up my Bootcamp somehow.

Initially there was a corrupted MBR table as other posts have dealt with, e.g. these:

https://discussions.apple.com/thread/252319323?login=true&sortBy=best

https://discussions.apple.com/thread/252776981?sortBy=best&page=3

How to convert a drive from the GPT format to the hybrid GPT/MBR format when using High Sierra (macOS 10.13.2)

I followed the instructions there (using fdisk, not gdisk) and on the face of it, everything looks fine - at least in my eyes. MacOS is of a different opinion unfortunately, so I am at a loss of what to do now. I provide some basic screen shots below, which hopefully might provide clues.

enter image description here

I do notice now that the gpt command shows "Suspicious MBR at sector 0" now - unsure if that actually was there earlier today.

enter image description here

Looking at the MBR it looks like this

enter image description here

The Bootcamp disk is available in all of the following situations:

  1. Disk utility in MacOS
  2. Finder (showing all individual files as well, and I can even copy files to Mac folders)
  3. In recovery mode (command+R) as a choice of bootable disk (will not boot though)
  4. Startup Disk (in System Preferences)

So, the basic problem is that it seems to be almost correctly configured, but not fully, and the disk is just not showing up while booting (and pressing Alt/Option).

UPDATE 09.03.2024 10.41 CET In order to exhaust all alternatives I did try with the Win7 boot drive again after having reset both SMC and NVRAM, but unresponsive keyboard and track pad remained.

I thereafter pursued the Win10 avenue instead and downloaded a "fresh" x64 version (ISO) from Microsoft's homepage and started creating a bootable flash drive (size 32 GB), using Boot Camp Assistant (BCA), from that ISO. However, BCA throws me an error message during the process some 15-20 minutes in, see below. enter image description here

I looked into this issue, which of course others have encountered. I tried the eject recommendation, but there was not any mountings to eject in my case really, and the one that popped up in Disk Utility could not be ejected as it was in use for the BCA process.

Terrible wall of problems this has turned into :)

Eniac
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  • The "Suspicious MBR at sector 0" is message is expected. The partition tables look OK. I suppose there may not be any boot code in the MBR. – David Anderson Mar 07 '24 at 20:05
  • @DavidAnderson First of all, I am glad to have your attention, as I did notice you were a contributor of solutions in previous posts. With "...there may not be any boot code...", do you mean that is the reason for the "Suspicious MBR at sector 0" part, or do you imply that this is the core reason why the Bootcamp disk is not showing up upon boot? I suppose there is a way to also verify the (possible) absence of boot code, or a way to "inject" it there? – Eniac Mar 07 '24 at 20:21

1 Answers1

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My 2007 iMac has a BIOS booting Windows 11 installed. I erased the code in the MBR and found the same problem reported in your question. Below are steps to correct the problem. You may not need all these steps, but I included extra steps in case there are additional problems.

  1. Use the Boot Camp Assistant to make a Windows 7 SP1 or Windows 10 bootable flash drive installer. A Windows 10 ISO file can be found here.

  2. Restart the Mac and immediately hold down the alt key untill the Mac Startup Manager icons appear.

  3. Select to boot from the flash drive.

  4. When either image below appears, press the key combination shift+F10 to open a command prompt window.

    windows 7

    windows 10

  5. Enter the following commands

    bootsect /nt60 c: /mbr
attrib -h -s c:\boot\bcd
del c:\boot\bcd
bootrec /rebuildbcd
exit

    When you get the following prompt, press the Y key followed by the return key.

    Add installation to boot list? Yes(Y)/No(N)/All(A):

  6. Turn off the Mac.

    If you booted from Windows 7 SP1 flash drive, then do the following. Select the sequence: Next > Repair your computer > Next > Shut Down.

    If you see the following popup, then select Repair and restart.

    problems

    If you booted from Windows 10 flash drive, then do the following. Select the sequence: Next > Repair your computer > Turn off your PC.

David Anderson
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  • Thanks for a detailed proposal. After the original post I did find your response in

    https://apple.stackexchange.com/questions/207721/repair-mbr-windows-10-from-os-x

    which sounded like up the right alley, so have been trying to test a little. However, the keyboard of the MBP is totally unresponsive after booting from the flash drive (getting your first image), and so are two different wired keyboards as well. So, neither track pad nor keyboards are responsive in that window. Presumably this is a different issue than the post, but it is kind of key to make any progress unfortunately.

     – Eniac Mar 08 '24 at 21:40
  • The Windows 10 ISO works better than the Windows 7 ISO with respect to using the keyboard. – David Anderson Mar 08 '24 at 21:58
  • If you cannot get keyboard or track pad to work when using Windows 10 ISO, let me know and I will post another alternative. – David Anderson Mar 09 '24 at 07:30
  • I am very appreciative of your patience. I posted an update with my efforts and their results. As you can see I am running into issues with that solution as well, unfortunately. If you have another suggestion I am all ears... I am starting to sense that preparations for damage control are called for, i.e. assessing what needs to be salvaged from that partition and what I can do without. – Eniac Mar 09 '24 at 10:01
  • If you cannot boot from a flash drive and get a keyboard or pointing device to work, then all I can offer is to substitute virtual devices. This would require installing software such as VirtualBox, then using a virtual machine and macOS Recovery to make the repairs. Most users at this point decide this would be too complex to take on. Unless you are interested, I will not elaborate. – David Anderson Mar 11 '24 at 19:46