Various issues with installing Windows

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Various issues with installing Windows

Hi all,

I've been trying to install Windows on my iMac well over a dozen times using various methods recommended on various forums such as this and I either cannot get into the Windows installer or the installer will not proceed past the "Copying installation files" part.

Below I will outline my specs, the various methods I've tried and the outcome. Please note that all the attempts were made after a fresh install of the latest Big Sur and using different Windows ISO versions (21H1, 20H2, 2004, 1909).

Hopefully someone will be able to help me resolve this.

Specs:

iMac (Retina 5K, 27-inch, 2019)

3GHz Intel Core i5

16GB DDR4

1TB NVME (OS, APFS)

1TB SSD (APFS)

Big Sur 11.5.2

Scenario 1 - Following the Boot Camp Assistant Guide:

SMC and PRAM reset
2x First Aid on Macintosh HD
Follow the Boot Camp Assistant Guide
Allocate 500gb to macOS and 500gb to Windows
Diskutil is open in the background, confirming OSXRESERVED and Bootcamp partition was created by Boot Camp Assistant
Boot Camp Assistant restarts the computer without prompting for a password (I noticed that some guides have mentioned that they had to type in a password before Boot Camp Assistant restarts the computer)
Apple logo stays on the screen for about 30 seconds
After this the flashing folder with a question mark logo appears
Power off iMac
Power on iMac
Boots into Big Sur
Diskutil shows Bootcamp partition, OSXRESERVED is no longer listed

Scenario 2 - Following the Boot Camp Assistant Guide + holding Option

SMC and PRAM reset
2x First Aid on Macintosh HD
Same process as Scenario 1 up to powering off iMac
Power on iMac while holding Option
Select Windows to boot
Installer starts
Commences to screen showing the setup progress
Does not progress past "Copying installation files (0%)
Error message pops up saying "Windows cannot locate the disk and partition specified in the unattend answer files <ImageInstall> setting. Make sure the setting references a valid partition and restart the installation."
Exits and reboots
Boots into Big Sur
Diskutil shows Bootcamp partition, OSXRESERVED is no longer listed

Scenario 3 - Following the Boot Camp Assistant Guide + holding Option v2

SMC and PRAM reset
2x First Aid on Macintosh HD
Same process as Scenario 1 up to Boot Camp Assistant restarting the computer
Hold down Option key just as Boot Camp Assistant restarts computer
Select Windows (or EFI) to boot
Installer starts
Commences to screen showing the setup progress
Does not progress past "Copying installation files (0%)
Error message pops up saying "Windows cannot locate the disk and partition specified in the unattend answer files <ImageInstall> setting. Make sure the setting references a valid partition and restart the installation."
Exits and reboots
Boots into Big Sur
Diskutil shows Bootcamp partition, OSXRESERVED is no longer listed

Scenario 4 - Manual install

Format USB 2.0 and USB 3.0 sticks in ExFAT and create a bootable USB with the various Windows ISO
Download the Windows Support Files via Boot Camp Assistant and copy to USBs
SMC and PRAM reset
Diskutil to partition the drive (500gb Windows ExFAT)
GPT fdisk confirms that the MBR partition is not hybrid and is protective
Restart
Hold down Option key
Boot from USB
Installer starts
Gets to "Where do you want to install Windows?"
Correct the partition by
- Deleting the newly created Windows partition
- Select the "Unallocated Space"
- Click "New" to create NTFS partition along with the other partitions Windows requires automatically
Select the newly created NTFS partition and click "Next"
There is an error message in the same window saying "We couldn't create a new partition or locate one."

Can anyone offer any tips or advice on anything else I can try to resolve this?

Thank you.

iMac Line (2012 and Later)

Posted on Aug 31, 2021 6:37 PM

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Answer 1

Top-ranking reply

Loner T

Level 9

59,513 points

Sep 1, 2021 4:31 AM in response to jacobim_mugatu

jacobim_mugatu wrote:

No, they are not configured as Fusion drive.

Is there a specific reason they are not?

Is there another way?

Not an easy one. You have to physically disconnect the drive you do not want to participate in Windows, install Windows which also means that this drive must also have macOS, and then connect the second drive. The designated Windows drive must be in the main 'slot/bay' of the Mac, otherwise it will not boot in Windows correctly. Also, after you connect the second drive, it is very hard to repair Windows, if there is any issue with the installation.

Be aware that third-party NVMe or SSD storage may not work properly with Windows.

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Answer 2

Loner T

Level 9

59,513 points

Sep 2, 2021 4:56 AM in response to jacobim_mugatu

A Fusion drive configuration will work with two solid-state drives. Newer macOS versions have a Disk Utility verb called resetFusion which has (from macOS Catalina)

diskutil resetFusion

Internally-located hardware disk device known to the currently-running macOS:
Solid State                              (disk0)

Volumes exported by partitions or storage systems hosted on the above device:
(none)                                   (disk0s3)
Macintosh HD - Data                      (disk1s1)
Macintosh HD                             (disk1s5)

At least one of your computer's internal disk devices must be solid-state

There is no performance loss if you use an SSD instead of a secondary HDD.

For APFS, see the description of '-main' and '-secondary'.

diskutil apfs createContainer 
Usage:  diskutil apfs createContainer <disk> [<disk>]
        diskutil apfs createContainer -main <disk> [-secondary <disk>]
        where <disk> = MountPoint|DiskIdentifier|DeviceNode
Create an empty APFS Container. You can then add APFS Volumes with the
diskutil apfs addVolume verb. If you specify two disks, then a "Fusion"
Container is created, with the performance usages assigned automatically
unless you use the -main and -secondary options, in which case, the secondary
disk is assumed to be on "slower" hardware. The secondary disk is often used
to store associated "auxiliary" data, such as a Boot Camp Assistant partition.
Ownership of any affected disks is required.
Example:  diskutil apfs createContainer disk0s2

On APFS systems, there is an additional requirement that the -secondary should be larger in size than the -main disk. I assume that is the case on your iMac.

On non-APFS macOS versions...

diskutil cs create
Usage:  diskutil coreStorage create lvgName
        MountPoint|DiskIdentifier|DeviceNode ...
Create a CoreStorage logical volume group from one or more disks.
The specified disks will become the initial set of PVs.
All existing data on the drive will be lost.
Ownership of the affected disks is required.
Example: diskutil coreStorage create MyLVG disk1

PVs reference physical volumes.

Your SSD is a SATA-connected SSD, which is rated at 6Gbps for SATA3. See Step 26 in iMac Intel 27-Inch Retina 5K. This SATA connection is your limit, whether you use a SSD or a HDD.

My recommendation is to

Backup both disks
Create a Fusion APFS configuration with the NVMe as -main and SSD as -secondary disks.
Restore your macOS backup
Install Windows via BC Assistant.

This makes you iMac a standard configuration that can be easily supported for both OSes. And you do not need to follow the 38 x 2 steps of unnecessary repair work 😉.

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Answer 3

Loner T

Level 9

59,513 points

Aug 31, 2021 8:38 PM in response to jacobim_mugatu

jacobim_mugatu wrote:

Specs:

iMac (Retina 5K, 27-inch, 2019)

3GHz Intel Core i5

16GB DDR4

1TB NVME (OS, APFS)

1TB SSD (APFS)

Big Sur 11.5.2

Are these two storage media configured as a Fusion drive? If not, then most gyrations for installing Windows will fail.

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Answer 4

Sep 1, 2021 9:07 PM in response to Loner T

Loner T wrote:

Is there a specific reason they are not?

Thanks for all your help so far. No specific reason on why they aren't configured as a Fusion drive. I'm pretty new to Apple products and I am still learning about this system. I could see the benefit in setting up a NVME/SSD and mechanical drive in a Fusion drive configuration, but from my (limited) understanding, there are no performance benefits in having a NVME and SSD configured in a Fusion drive configuration. Also, I've read somewhere that Fusion drive configuration only works when one drive is a solid state and the other is a mechanical drive. Not sure if that's true or not.

Not an easy one. You have to physically disconnect the drive you do not want to participate in Windows, install Windows which also means that this drive must also have macOS, and then connect the second drive. The designated Windows drive must be in the main 'slot/bay' of the Mac, otherwise it will not boot in Windows correctly. Also, after you connect the second drive, it is very hard to repair Windows, if there is any issue with the installation.

Be aware that third-party NVMe or SSD storage may not work properly with Windows.

This was something I didn't want to resort to, but I guess I'll have to. So just to be clear (before I open it up) - after I disconnect the second drive (non OS), Windows is installed and set up correctly, and finally, reconnect the second drive, there shoudn't be any issues with booting into either MacOS or Windows?

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Answer 5

Sep 2, 2021 6:45 AM in response to Loner T

Loner T wrote:

On APFS systems, there is an additional requirement that the -secondary should be larger in size than the -main disk. I assume that is the case on your iMac.

Both my main and secondary are the same size as shown in the diskutil list output:

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                 Apple_APFS Container disk3         1000.0 GB  disk0s2

/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_APFS Container disk2         1000.0 GB  disk1s2

/dev/disk2 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +1000.0 GB  disk2
                                 Physical Store disk1s2
   1:                APFS Volume Stuff                   43.3 GB    disk2s1

/dev/disk3 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +1000.0 GB  disk3
                                 Physical Store disk0s2
   1:                APFS Volume Macintosh HD — Data     40.3 GB    disk3s1
   2:                APFS Volume Preboot                 283.4 MB   disk3s2
   3:                APFS Volume Recovery                626.2 MB   disk3s3
   4:                APFS Volume VM                      1.1 MB     disk3s4
   5:                APFS Volume Macintosh HD            15.3 GB    disk3s5
   6:              APFS Snapshot com.apple.os.update-... 15.3 GB    disk3s5s1

Just to double confirm - due to the above, I will not be able to create a Fusion APFS configuration with the NVME and SSD? Meaning I definitely have to perform unnecessary repair work to get this sorted out?

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Answer 6

Sep 4, 2021 7:26 PM in response to jacobim_mugatu

Was able to resetFusion successfully, rebooted and installed macOS. Ran diskutil first aid, reset PRAM, then without restoring any backups, I ran Boot Camp Assistant and an error popped up saying something along the lines of "there is 0 bytes of free space to partition the drive..."

Diskutil shows 1.98TB free.

Checked diskutil resizecontainer limits and it shows that the Minimum, Recommended Minimum and Maximum figures were all the same, which was odd. Tried to resize manually and it wouldn't work.

Tried deleting snapshot and rebooted. Boot Camp Assistant popped up with the same error.

Ran resetFusion again and went through the install process again. Same result.

I needed Windows set up for some of my work, so didn't have much time left to troubleshoot. I ended up splitting the Fusion, pulled the screen off just enough to reach my hand in to disconnect the SATA plug to my SSD. Then installed macOS, ran Boot Camp Assistant and Windows successfully installed without a single problem. Pulled the screen off again to plug the SSD back in. Tested everything to make sure there were no errors, then finally replaced the adhesive for the screen. This ended up being a much quicker way to resolve the issue for me.

Thanks for all your help, Loner T! Have learnt a lot and I'm glad it's finally resolved.

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Answer 7

Loner T

Level 9

59,513 points

Sep 5, 2021 5:17 AM in response to jacobim_mugatu

Good to see it working, for now! You may need to troubleshoot further. Given the current configuration, if Windows is corrupted for any reason, you will need to remove it, which means you will face the same issue(s) again.

jacobim_mugatu wrote:

Was able to resetFusion successfully, rebooted and installed macOS. Ran diskutil first aid, reset PRAM, then without restoring any backups, I ran Boot Camp Assistant and an error popped up saying something along the lines of "there is 0 bytes of free space to partition the drive..."

Diskutil shows 1.98TB free.

It would be good to see the actual APFS configuration. resetFusion with SSDs can be problematic.

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Answer 8

Aug 31, 2021 10:56 PM in response to Loner T

No, they are not configured as Fusion drive. Is there another way?

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Answer 9

Loner T

Level 9

59,513 points

Sep 2, 2021 8:11 AM in response to jacobim_mugatu

If you have a backup of both your disks, I suggest you try to resetFusion and check for any errors, before we try to rebuild the Fusion configuration manually.

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Answer 10

Sep 2, 2021 5:34 PM in response to Loner T

I will try this and report back. Thanks!

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