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[Solved] Make existing Windows drive bootable again after High Sierra install

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I've just recently performed a fresh install of High Sierra overwriting my existing Sierra Install. This installation is on its own SSD. The High Sierra installation so far appears to be running fine without too many hiccups.

I also had a Windows 10 installation on a separate SSD which was previously working fine as a dual boot option alongside Sierra.

After the High Sierra install the Windows drive is no longer bootable. I cannot access it from Clover as it's only showing 3 drives which are legacy windows drives, none of which are bootable - once clicked on they just display a blinking cursor. I cannot boot the Windows drive from the BIOS startup boot options either. The Windows drive actually appears to be missing from these BIOS startup boot options. I used to just press f12 and boot windows that way but can no longer do that.

I'm wondering what the easiest way is to make Windows drive bootable again without affecting my High Sierra installation?
 

UtterDisbelief

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I've just recently performed a fresh install of High Sierra overwriting my existing Sierra Install. This installation is on its own SSD. The High Sierra installation so far appears to be running fine without too many hiccups.

I also had a Windows 10 installation on a separate SSD which was previously working fine as a dual boot option alongside Sierra.

After the High Sierra install the Windows drive is no longer bootable. I cannot access it from Clover as it's only showing 3 drives which are legacy windows drives, none of which are bootable - once clicked on they just display a blinking cursor. I cannot boot the Windows drive from the BIOS startup boot options either. The Windows drive actually appears to be missing from these BIOS startup boot options. I used to just press f12 and boot windows that way but can no longer do that.

I'm wondering what the easiest way is to make Windows drive bootable again without affecting my High Sierra installation?

Well, first up, don't do what I mention unless you take precautions beforehand. I don't think you can lose anything but you need to copy/backup anything vital that you can just I case...

A part of the problem could be that High Sierra has configured itself with the APFS file system, unless you over-rode the option and went with HFS+ which partitions disks in a more straight-forward manner.

I would disconnect the HS drive to prevent any confusion or further damage to either. Then - do you have a Windows CD or ISO ?

In the old days you could boot from the CD/DVD Windows disk and at the DOS-style menu chose to Repair the setup rather than do a full install. You can check the Windows disk format and partitions to make sure they are correct and repair as necessary.

You can create a bootable USB stick with your ISO if a disk isn't handy - and use that to enter the Setup routine and Repair. Or, if you like, you can use DiskUtil to create a bootable CD/DVD from the ISO before disconnecting the HS drive.

Just a couple of ideas. Maybe someone else will post an easier option... :)
 
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Thanks for the prompt assistance! Yes HS was installed with APFS. And yea I should be able to track down windows ISO. I shall give the repair option a go later in the week.

My HS install is on an m2 ssd, so rather than pull it out to disconnect, is it safe enough to just disable it from the BIOS? Does disabling the drives affect the EFI drives and bootloaders?
 
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I managed to sort it out!

To help others here is what I did:
  1. Cloned the High Sierra drive to another SSD for precaution
  2. Disabled the sata port in the BIOS for the m2 SSD which contained the High Sierra install.
  3. Booted from the Windows Install Disc.
  4. Attempted to repair using the basic startup repair options. This did not work as it could not find the OS.
  5. From the windows cd troubleshooting options, selected command prompt option, and used the following commands:
    bootrec.exe /fixmbr
    bootrec.exe /fixboot
  6. After a reboot, I was then able to boot from the Windows drive using the startup boot options.
  7. I re-enabled the sata port for the HS install which re-enabled the clover bootloader again.
  8. High Sierra booting from clover also tested fine.
  9. Tested the windows drive and osx drive again - both now booting fine again as before.

Thanks again for the direction Utter!
 

UtterDisbelief

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I managed to sort it out!

To help others here is what I did:
  1. Cloned the High Sierra drive to another SSD for precaution
  2. Disabled the sata port in the BIOS for the m2 SSD which contained the High Sierra install.
  3. Booted from the Windows Install Disc.
  4. Attempted to repair using the basic startup repair options. This did not work as it could not find the OS.
  5. From the windows cd troubleshooting options, selected command prompt option, and used the following commands:
    bootrec.exe /fixmbr
    bootrec.exe /fixboot
  6. After a reboot, I was then able to boot from the Windows drive using the startup boot options.
  7. I re-enabled the sata port for the HS install which re-enabled the clover bootloader again.
  8. High Sierra booting from clover also tested fine.
  9. Tested the windows drive and osx drive again - both now booting fine again as before.

Thanks again for the direction Utter!

Good news :thumbup:

Good idea isolating the m.2 SSD using the BIOS. I only have SATA SSDs so it never occurred. That's a tip to store for the future!

:)
 
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