Failed Win 10 install on Bootcamp High Sierra

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Level 1

8 points

Failed Win 10 install on Bootcamp High Sierra

I have iMac 27" late 2013 with 3 tb fusion drive with High Sierra installed on a single Mac OS partition.

I am trying unsuccessfully to install Windows 10 on a Bootcamp partition (ca 600GB).

Everything is going well until the Windows installer goes into "Finalizing" section when I constantly get an error saying "Windows could not prepare the computer to boot into the next phase". I have tried few times to install with different partition size, resetting NVRAM, reinstalling High Sierra on clean disk. I am able to delete this partition and try another install to no avail.

Any suggestions please? If anyone had the same problem and solved it I would appreciate your help.

Piotrek

iMac

Posted on Nov 13, 2017 9:49 AM

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Answer 1

Piotrek L. Author

Level 1

8 points

Nov 14, 2017 4:12 AM in response to Loner T

Hello Loner T,

appreciate you are trying to help. Here is the current situation:

- I resetted SMC and NVRAM just before another attempt to install Win 10 (version 1607 iso)

- Tried BCA install with the same error

- BCA made NTFS partition (ca 685GB) and the installation stopped

See attached pictures (Disk Utility in Polish but I guess it's not a big deal).

I hope this can be solved somehow. Thanks!

Piotr

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Answer 2

Piotrek L. Author

Level 1

8 points

Nov 13, 2017 12:58 PM in response to Loner T

Hello again,

Unfortunately it doesn't work. Still the same error at the exactly same moment of installation.

I was able to install Windows before when I had Sierra and older Mac OS.

It seems like High Sierra doesn't work well with BC.

If it helps I am attaching diskutil cs list:

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Answer 3

Loner T

Level 9

59,471 points

Nov 13, 2017 3:10 PM in response to Piotrek L.

Create a partition using BCA, try to install, and let it fail. Then we can inspect the partitions and check what is wrong with the partitions or the installation. Also, you must NVRAM and SMC reset, every time the installation fails, before you make the next attempt.

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Answer 4

Loner T

Level 9

59,471 points

Nov 14, 2017 6:01 AM in response to Piotrek L.

Disk1s4 is outside the 2TB boundary. If your installer is using legacy BIOS, this will not work. Your late 2013 model supports both legacy BIOS and EFI boot. For EFI Boot to work, the ESP (EFI) partition also needs to be updated with Microsoft EFI information.

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Answer 5

Piotrek L. Author

Level 1

8 points

Nov 14, 2017 10:35 AM in response to Loner T

Tested it. Booted from USB EFI Boot.

I get "Setup was unable to create a new system partition or locate an existing system partition" error during partition selection. I just cannot install on existing BC partition created via Bootcamp.

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Answer 6

Loner T

Level 9

59,471 points

Nov 14, 2017 11:10 AM in response to Piotrek L.

The following command converts the FAT32 to Free Space, so disk1s4 will no longer exist. Please run the following command only once, otherwise you will lose data.

diskutil eraseVolume free free disk1s4

Now, use EFI Boot and point to this Free Space, which it will split into a 128MB Microsoft Reserved and the rest will be NTFS. If it does not work, we can cleanup and merge the disk space back into the CS volume.

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