Cannot partition a disc with Boot Camp Assistant - Manual install Windows 10

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Cannot partition a disc with Boot Camp Assistant - Manual install Windows 10

iMac: Late 2013. Running 10.14.3 (Mojave). Just reformatted this and did a clean install (due to it running exceedingly slow and hanging up all the time)

So I am having major issues trying to get Boot camp to work with this computer. First, the "Install or Remove Windows 10" was grayed out in Boot Camp Assistant (and if I tried to manually partition the drive, it said the drive couldn't be smaller that 1TB). I managed to trace that to a seemingly obscure issue with Time Machine Snapshots. I deleted all the local Snapshots, and viola, the install button was available.

So thought I was good to go, but noooo. When I create the boot camp partition, it slows/stops at about 60% complete, and stays there. Admittedly I did not give it more than a few hours, but it just shouldn't take this long. I reset Pram, unplugged the computer, ran repair disc, booted in to internet recovery mode and ran repair disc (from terminal too). Nothing is helping. I decided to try and create a partition manually, naming it BOOTCAMP - I was JUST about to post it didn't work, but it just finished successfully. I know I saw a post this evening listing the steps necessary to manually go through the process, but I cannot find that anymore (arrrggg), so since I am already hear and couldn't hurt to ask....

So can I just boot into the EFI volume, start the process there and complete my installation? I have already created a USB drive with Windows 10 and downloaded all the drivers, and I can boot into the EFI volume and start the installation process (I already tried that). What do I need to pay attention to if BCA isn't holding my hand the whole way through? When and how are the drivers installed that were supposedly downloaded when I create the bootable USB? It has been a while since I did this and all the other times I tried it worked straightaway. And this computer in a previous life did have windows on it.

Thanks!

iMac 27", 10.14

Posted on Feb 4, 2019 12:20 AM

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Answer 1

Best reply

Loner T

Level 9

59,471 points

Feb 4, 2019 3:42 AM in response to Gregory Kinney

On your USB2 Flash drive, you should have a $WinPEDriver$ folder which should contain all the drivers. If you are manually going to install using EFI Boot, you will need to delete the MBR that BC Assistant may have created. You should convert the current FAT BC partition to Free Space for the installer to build a MSR/MSD part and install Windows.

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Answer 2

Feb 4, 2019 8:09 AM in response to Loner T

Thanks a lot for the reply. A couple questions. First, any idea why BCA kept failing at the partition while Disk Utility succeeded? It is a little bothersome that there is some underlying problem with the disk.

Also, I understand that I have to delete the Fat32 partition and have the Windows Installer reformat NTFS. However I get the feeling that what you are referring to - deleting the MBR that BCA may have created - is different. I found a thread of yours form a while ago that discusses but I admit I am still unsure what to do there. Is this what you are talking about/I need to do?:

Once you add a FAT32 partition with either Boot Camp Assistant or Disk Utility, your disk is converted into a hybrid GPT / MBR disk which is actually not supported by newer versions of Windows hence the problems I was having with a new purchase of Windows 10 and lots of people will be in the same situation. In this step, we revert this additional change made by Disk Utility by switching back to a pure GPT partition table.

1 - Download the latest version of GPT fdisk from https://sourceforge.net/projects/gptfdisk/files/gptfdisk/ by browsing to the version, then gdisk-binaries and clicking the file with the *.pkg extension (e.g. gdisk-1.0.1.pkg).

2 - Install GPT fdisk by running the installer you downloaded

3 - Open a Terminal and check the state of your MBR using the command ‘sudo gdisk /dev/disk0’ and if your MBR partition is set to hybrid, please continue with the instructions below otherwise if it is set to protective. simply type q and hit return to exit GPT fdisk

4 - Type p to view the existing partition table and verify you’re working on the correct disk

5 - Type x to enter the expert menu

6 - Type n to create a fresh protective MBR

7 - Type w to save your changes and confirm the change when asked

8 - Type q to exit GPT fdisk

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