The folks at Apple seem to be operating under a paradigm where no drive space is ever unallocated. Therefore, when System Integrity Protection (SIP) is enabled, the macOS operating system prevents execution of any utilities or commands which could report the location of lost space on system drives. Your Mac uses a single
physical system drive named /dev/disk0.
System drives generally contains two types of partition tables. The first is the Master Boot Record (MBR) table and the second is the GUID Partition Table (GPT). The command fdisk dumps the contents of the MBR table, while the command gpt partially dumps the contents of the GPT. To used these command on a system drive, you need to either disable SIP or execute the commands while booted to macOS Recovery. The commands you need to enter are given below
fdisk /dev/disk0
gpt -r show /dev/disk0
The gpt commands prints a table of the space occupied by each partition. The table also prints unallocated space. Generally, you need to know which partitions are located before the lost (unallocated) space you wish to recover. Usually, the diskutil command can then used to recovery this space. Although, other commands such as fdisk, gpt and gdisk can also be used.
Note: Generally the identifier produced by disktuil output contains the index for a given partition. This is not alway true. You may need to consider other output from both the diskutil and gpt commands before matching a partition index with an identifier.
If you could post the output from the above commands, then someone (or I) could help with the correct commands to repair your Mac.
Update 1
You can erase the Apple_KernelCoreDump` partition by executing the command given below. The result will a block of free space the the end of your drive. The size of this block will be about 61 GB.
sudo diskutil erasevolume free n disk0s5
Beyond this change, I am not sure what to post. I need to know how you want the drive partitioned. So far, you have mentioned partitions for ExFat and Windows. Currently you have Apple_HFS and Apple_Boot partitions. You can not merge the free space back to the APFS container until these partitions are erased. Also, if you are going to reinstall Windows, you probably should state the model/year of your Mac and the version of Windows.
Update 2
The following command will return all free space back to the APFS partition.
sudo diskutil erasevolume free n disk0s3
sudo diskutil apfs resizecontainer disk0s2 0
If the above commands work, are you then going to attempt to install Windows 10 through the use of the Boot Camp Assistant? Other users have reported problems using the Boot Camp Assistant when the internal physical drive has an APFS partition.
You can change the default to boot High Sierra by either of the following:
- Select High Sierra from the Startup Disk pain of the System Preferences application.
- Hold down the control key when selecting High Sierra from the Startup Manager.
You still have Mojave code in your APFS container. In your case, do the opposite of the answer you linked to.
BTW: You can also elect to not delete this code. The code will not interfere with the operation of the Mac and occupies very little space.
IN OTHER WORDS:
Note: Below I have assumed APFS Volume "Preboot" is disk2s2 and APFS Volume "My Recovery" is disk2s3.
You can use Disk Utility under High Sierra to remove the APFS volume containing Mojave. However, removing Mojave also requires steps where commands are issued in a Terminal application window. Below are the remain steps needed to remove Mojave.
- Open the Disk Utility application.
- Get the file system UUID of the High Sierra volume . Right click the icon for the High Sierra volume in the Disk Utility application and select
Get Info. Here, I will assume the file system UUID is 2E0E6320-5D0A-4181-B465-ABFF2CBBFC27.
- Boot to macOS Recovery.
- Open a Terminal application window.
Enter the command below to disable System Integrity Protect (SIP) on next restart.
sudo csrutil disable
Boot back to High Sierra.
Open a Terminal application Window.
Determine the UUID of the deleted APFS Mojave volume. Start by entering the commands given below.
diskutil mount disk2s2
cd /Volumes/Preboot
ls
The UUID of the deleted APFS Mojave volume should be the same as the name of the directory (folder) that is not the UUID for the High Sierra volume (2E0E6320-5D0A-4181-B465-ABFF2CBBFC27). Here, I will assume this is 832D1AE3-C9F2-454F-BE45-64E1ECBA38AA.
Enter the commands below to remove Mojave from APFS Volume Preboot.
rm -Rf 832D1AE3-C9F2-454F-BE45-64E1ECBA38AA
cd ~
diskutil unmount disk2s2
Enter the commands below to remove Mojave from APFS Volume My Recovery.
diskutil mount disk2s3
cd "/Volumes/My Recovery"
rm -Rf 832D1AE3-C9F2-454F-BE45-64E1ECBA38AA
cd ~
diskutil unmount disk2s3
Reset the SIP settings, by entering the command given below.
sudo csrutil clear
Restart the Mac
Best Answer
I would say you need 2 systems and one third volume to do this the right way. It’s long been possible and sometimes preferred to have your user home folder apart from the boot system.
You will certainly have some breakage and possibly much breakage when you use things like Photo Library, podcasts, music and more when the 10.15 system reads the data structure and modifies / migrates then in the user folder on disk to a newer structure. When the OS boots back to 10.14 this breakage will show and depending on your needs, you might need to keep two parallel home systems, so I would make a good backup of the 10.14 side before you boot to 10.15 and open anything more complicated than isolated documents.