Unable to install Windows 10 on late 2015 iMac fusion drive (boot camp)

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TerryakiP Author

Level 1

8 points

Unable to install Windows 10 on late 2015 iMac fusion drive (boot camp)

I have been running Windows on this iMac since the Mojave fusion drive Windows fix.

Since upgrade to Big Sur, the Windows is broken and I’m trying to reinstall everything again.

here are the specs of my iMac:

Late 2015 iMac 27”
intel i7 4 GHz
32 GB DDR3
3TB fusion drive
ethernet connection
unplug everything from iMac (using touchpad only)

I have run the diskutil resetFusion to clean the fusion drive.
reinstall Big Sur
download the latest version of Windows 10
run BCA on iMac.
create a 500 GB drive for Windows 10
the BCA restarts my iMac and runs the Windows 10 installation.
format BOOTCAMP
Install Windows 10
*system is unable to create a new system partition or locate an existing system partition. See the setup log files for more information.*

could anyone help with this?

thanks.

terry

Posted on Apr 6, 2021 10:16 PM

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Answer 1

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Loner T

Level 9

59,513 points

Apr 6, 2021 10:39 PM in response to TerryakiP

TerryakiP wrote:

9. *system is unable to create a new system partition or locate an existing system partition. See the setup log files for more information.*

Do you have any external storage connected to the iMac? If yes, remove it. You should only have Keyboard/Mouse/Trackpad connected to the iMac.

Also, every failed attempt requires that you run a SMC and NVRAM Reset, before the next attempt at installing Windows. Be aware that Big Sur EFI has many issues with W10.

How to reset the SMC of your Mac - Apple Support

Reset NVRAM or PRAM on your Mac - Apple Support

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