Boot Camp Trouble

You will temporarily need to disable SIP using csrutil in Local Recovery (not Internet Recovery) otherwise GDisk will fail. Once SIP is disabled, the GDisk steps are as follows. Be aware that Reboots can change the disk numbers. I will assume disk0 is the 3TB HDD. Change it, if necessary, after you check the output of diskutil list.

Rebuild MBR to match the new GPT information thus resetting the Hybrid MBR. Use defaults for other questions (like partition codes). The only values that need modifications are the Boot flags and step 10. Accept all other defaults that Gdisk offers. Please see thesample Q&A as an example. These steps can be repeated if you make a mistake before you get to Step 12, otherwise start from Step 1 for these steps. Step 6 has numbers which are typed with a space between the numbers. Please see the sample Q&A before you execute these steps.



1. Sudo gdisk /dev/rdisk0
2. P (Print list of parts)
3. R (Recover)
4. O (print current Hybrid MBR)
5. H (chooses Hybrid)
6. Partitions numbers to be hybridized: 2 3
7. Y (Good for GRUB question)
8. N (part 2 boot flag)
9. Y (part 3 boot flag make NTFS bootable partition)
10. O (print current Hybrid MBR)
11. W (Write the new MBR)
12. Y (Yes! write the new MBR)
13. Reboot

Here is sample Q&A for this section. Please notice the Press Enter/Return.

Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): Y

Creating entry for GPT partition #2 (MBR partition #2)

Enter an MBR hex code (default AF): Press Enter/Return

Set the bootable flag? (Y/N): N

Creating entry for GPT partition #3 (MBR partition #3)

Enter an MBR hex code (default 07): Press Enter/Return

Set the bootable flag? (Y/N): Y

Assuming this is related to "Your disk could not be partitioned&#… - Apple Community,

• Try using W10 1803 (April) instead of W10 1809 (October)
• Your Mac supports both EFI and BIOS boots. Mojave defaults to EFI Boot. If you need to create a MBR, you can use GPT Fdisk (https://sourceforge.net/projects/gptfdisk/).
• The ISO should be on the Mac's internal disk in any folder other than Downloads.
• If BCA prompts you for a USB to create an installer, use a USB2 Flash drive, which will be erased and formatted by BCA.

My recommendation

• Use a USB2 Flash drive
• Download and install GPT Fdisk
• Create a FAT32 partition of 1+TiB
• I can provide steps for a Hybrid MBR in this configuration
• Test BIOS Mode Windows installation

Please do not switch macOS versions, yet! There are some peculiarities that need to be understood. Under Sierra

• BC Assistant forces W7 installation to use BIOS, EFI is not supported, even though the 2014 iMac is capable of EFI. BC drivers used are 5.1.5679.
• BC Assistant uses EFI during W10 installation, not BIOS, which causes a BSoD in win32kfull.sys. No MBR is created for W10.
• Mojave only supports W10 and EFI only for new installations, similar to Sierra, and ends up with the same BSoD.
• I manually partitioned the Fusion drive (CoreStorage, not APFS Fusion) using diskutil cs resizeStack command to get an MBR. This allowed me to install W10 1803 (April) using BIOS mode. Mojave has no equivalent of resizeStack command, but GPT FDisk can be used to create a MBR.
• My assumption is that Mojave supports grandfathered installations of non-W10 versions on ALL Macs, and should allow existing installations to continue. I have tested this on a 2012 MBP which was upgraded from macOS Yosemite to Mojave directly. I do not want Mojave on my 2014 iMac.
• I have seen some discussions, where users have lost their MBR, but Windows worked properly after MBR was recreated. See
  • windows 7 wont statrt - Apple Community
  • Unable to install Windows 10 - Apple Community
• The second link is still work-in-progress.
• I need to check which driver(s) may be causing the BSoD under Mojave/EFI on the 2014 iMacs.

brandonschuk wrote:

I have successfully removed the current partition, and I created a partition slightly over 1TiB. There is a "$WinPEDriver$" folder and here is a link to the PasteBin of my AutoUnattend.xml file: https://pastebin.com/YVzkf5xe

Looks fine and as expected.

Since it may have something to do with drivers on the windows boot drive, I am toying around right now with what happens if I use these contents instead of what the Windows10 boot drive has and/or a combination - no success yet, but will let you know.

https://support.apple.com/kb/DL1837?viewlocale=en_US&locale=en_US

BC 5.x drivers will fail on W10. You need to use BC6 drivers. Can you post a two-level file structure of $WinPEDriver$ using macOS Finder. Check the Product Version line in Bootcamp.xml referenced in the AutoUnattend.xml.

Lastly, what do you think of me trying to install windows 7 instead of windows 10 and then upgrading to windows 10? I would give it a shot, but I have been stuck for a few hours on how to make a windows 7 boot flash drive, because boot camp assistant will only let me make a windows 10 one, and will not allow me to make a windows 7 one. None of the manual ways seem to be working.

Mojave does not support W7. If you downgrade to Sierra, you may be able to, but EFI updates can lead to other issues.

W7 on the 2014 iMac 5K.

AMD Driver from 2014...

Disk layout (with MBR/BIOS).

 diskutil list 
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *121.3 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:          Apple_CoreStorage Macintosh HD            121.0 GB   disk0s2
   3:                 Apple_Boot Boot OS X               134.2 MB   disk0s3

/dev/disk1 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk1
   1:                        EFI EFI                     209.7 MB   disk1s1
   2:          Apple_CoreStorage Macintosh HD            743.3 GB   disk1s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk1s3
   4:       Microsoft Basic Data BOOTCAMP                256.0 GB   disk1s4

/dev/disk2 (internal, virtual):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                  Apple_HFS Macintosh HD           +858.8 GB   disk2
                                 Logical Volume on disk0s2, disk1s2
                                 E42F07F4-DBC6-4718-A535-5F0E83C319C5
                                 Unencrypted Fusion Drive

sudo fdisk /dev/disk1
Password:
Disk: /dev/disk1	geometry: 121601/255/63 [1953525168 sectors]
Signature: 0xAA55
         Starting       Ending
 #: id  cyl  hd sec -  cyl  hd sec [     start -       size]
------------------------------------------------------------------------
 1: EE 1023 254  63 - 1023 254  63 [         1 -     409639] <Unknown ID>
 2: AC 1023 254  63 - 1023 254  63 [    409640 - 1451845952] <Unknown ID>
 3: AB 1023 254  63 - 1023 254  63 [1452255592 -    1269536] Darwin Boot 
*4: 07 1023 254  63 - 1023 254  63 [1453527040 -  499996672] HPFS/QNX/AUX

I will post W10 EFI shortly.

Can you post the output of

diskutil list

and I can provide detailed steps for the MBR.

The MBR can be removed, without any changes to the GPT. This is to test if we can get past the EFI issues.

See Partitioning disk taking too long - Apple Community (start on page 11). Terminal commands are much more useful than a point-and-click UI. 😉

macOS Sierra. Apfs is problematic.