Boot Camp Won’t Work With macOS Mojave on 2012 27-Inch iMac With 3TB Hard Drive

[neek]

BTW: I tried to rescue the Bootcamp Vol, which is still shown in the finder with Twocows "Winclone 7" - Image is not available for restore to another drive.

I was able to mount the bootcamp.dmg and Winclone imaged that mounted volume. Imaging the BOOTCAMP_VOL is not useful. Mount the DMG inside BOOTCAMP_VOL and use Winclone to image the mounted disk image.

I've just completed a backup, reformat, and restore to move the system back to HFS+ and CoreStorage. (only 21 hours of copying). Will try to setup Bootcamp again and restore my image over the next couple of days.

 

[lec0rsaire]

Well this means I need to invest in new hardware, though. Not something I planned simply to be able to update to the latest macOS...
Just to clarify, you suggest to put Mojave on an external SSD?

Sorry. The boot camp Windows 10 on external! You will need to use a Windows machine or a VM of Win 10 through virtual box or VMWare to prepare the external SSD with an app called WintoUSB. You also need to save the Bootcamp drivers from Boot Camp Assistant. You can download them from the menu bar in BCA. There are several YouTube videos that show the whole process. Since it’s an iMac and not portable, it is not an inconvenience since you won’t have to carry stuff around like you would with a MBP or something.
[doublepost=1537979908][/doublepost]

Well this means I need to invest in new hardware, though. Not something I planned simply to be able to update to the latest macOS...
Just to clarify, you suggest to put Mojave on an external SSD?

They are also very, very cheap today. I think around $100 for Samsung T5 500GB. $249 for 1TB. They also run up to USB 3.1 gen 2 speeds (10Gbps) or essentially Thunderbolt 1. You can use them in the event that you buy a new TB3 MBP or iMac later on since this spec will be around for a while. Not the $400 that the TB2 SSDs usually cost. They will be fast enough for running games. I’ve seen many people do it.

 

[Shoju]

Curious as to what program (software) - procedure you are using to Back-Up your BootCamp (Windows 10) OS?

I was using Win10's native recovery options. Used it to create a full image of the BootCamp partition.
[doublepost=1538070502][/doublepost]I give up. I backed up my BootCamp partition and deleted it in order to be able to install Mojave. Now that I'm on Mojave it's impossible to partition the drive for a new BootCamp partition. The BootCamp Assistant keeps stopping in the middle of partitioning, telling me "the drive could not be partitioned", "an error occurred" and that I should run Disk Utility in order to "find the error and correct it". I did all that even when booting in recovery mode. Disk Utility says the drive is okay but partitioning with the BootCamp Assistant still fails.
F%$k this sh$t.
[doublepost=1538070708][/doublepost]

They are also very, very cheap today. I think around $100 for Samsung T5 500GB. $249 for 1TB. They also run up to USB 3.1 gen 2 speeds (10Gbps) or essentially Thunderbolt 1. You can use them in the event that you buy a new TB3 MBP or iMac later on since this spec will be around for a while. Not the $400 that the TB2 SSDs usually cost. They will be fast enough for running games. I’ve seen many people do it.

Thanks for the info, good to know. That's still $100 I wasn't planning on spending...

 

[jqworle]

I,m another one where Mojave broke my win 10 bootcamp which worked fine in High Sierra on a late 2014 iMac 27 3TB fusion drive.tried everything to get bootcamp to run including a clean install of Mojave’s but bootcamp always fails during the partitioning of the disk. I have now resorted to restoring High Sierra from my time machine backup and even that wasn’t easy as I had to delete the partition as disk utility only gave me the option of APFS at first until deleted it , and then I had options of hfs+ available again.

 

[jqworle]

High Sierra back working but still cant load windows , it creates partition but when you select the bootcamp partition to actually install windows it gives an error message saying no partition formatted even though it is there and ntfs according to disk utility.

 

[Trancegiving]

I was using Win10's native recovery options. Used it to create a full image of the BootCamp partition.
[doublepost=1538070502][/doublepost]I give up. I backed up my BootCamp partition and deleted it in order to be able to install Mojave. Now that I'm on Mojave it's impossible to partition the drive for a new BootCamp partition. The BootCamp Assistant keeps stopping in the middle of partitioning, telling me "the drive could not be partitioned", "an error occurred" and that I should run Disk Utility in order to "find the error and correct it". I did all that even when booting in recovery mode. Disk Utility says the drive is okay but partitioning with the BootCamp Assistant still fails.
F%$k this sh$t.
[doublepost=1538070708][/doublepost]Thanks for the info, good to know. That's still $100 I wasn't planning on spending...

I am Back at High Sierra after a complete Reinstall to it without a Backup. Will add a new Bootcamp now, but how did you manage the recovery of the .dmg Image ? I copied the bootcamp_Vol.dmg to an external Disk as a backup before Reinstalling High Sierra. How can I use this file now ? Thx for a detailed Reply and Greets to Berlin from HH. Danke vorab !

 

[Shoju]

Okay, so I didn't give up after all. I wanted this to work and even though it's probably just a bug that Apple may fix at some time in the future I didn't want to wait for that.
I'll try to be as detailed as possible tracing back the steps I took in order to get my late 2014 iMac with a 3TB Fusion Drive to not only run Mojave but also Win10 from a Bootcamp partition. Yes, that's right, I succeeded. Mostly. Here we go.

Let's recollect: Bootcamp Assistant failed to create a partition time and time again even though Disk Utility told me there's nothing wrong with the drive. Well, it turned out there was something wrong but I merely found that out by chance.
I was researching the web trying to find answers to my issue when I stumbled upon this support post by Apple regarding fixing a 'split' Fusion Drive.
While the symptoms explained in that post didn't match my problem, I still felt like trying this out as it sounded like something that may help in my situation. Note that those steps "permanently delete all data stored on the drives that make up your Fusion Drive. Make sure that you have a backup before continuing".
Going through each step in the Terminal I found out that my drive had a lot more partitions than what Disk Utility displayed before (see IMG_0014.jpeg).
After completing the steps to fix the drive I re-installed Mojave on my now completely wiped Fusion Drive. Don't make the mistake of restoring your Mac from your Time Machine backup immediately after that (I had to undergo above steps twice because I did).
Set your Mac up as new and launch Bootcamp Assistant right after in order to finally create that partition you wanted for so long (I know I did)... It should work fine now.
Now, when booting into Windows setup I ran into new problems. Although Bootcamp formatted the partition in NTFS Windows Setup didn't want to recognize it as such (see IMG_0015.jpeg).
I did some research online again and found another source (in German, sorry) where the author suggests to reformat the Bootcamp partition with Disk Utility into the ExFAT format. Afterwards restart your Mac holding the alt key in order for it to display available boot drives. Choosing 'EFI Boot' is suggested. Windows Setup should now be able to work with the partition (it didn't for me) but you may have to format it again first from within the installer (that still didn't work for me) and if that doesn't help: "delete it and choose the free space for installing Windows". The latter did work indeed and I was finally able to install Win10.
Yay, right? Well... When I wanted to go back to macOS choosing "restart under macOS" from Win10's Bootcamp menu I got an error message telling me Bootcamp can't find the macOS start volume and thus can't reboot (see IMG_0027.jpeg).
I restarted my Mac holding the alt key again and after I was back in Mojave chose macOS as start volume in settings and restarted my Mac again. After that procedure my Mac booted into macOS by default again. Phew. I restored my programs and files from my Time Machine backup afterwards.

So here we are: I now have Win10 on a Bootcamp partition installed on a late 2014 iMac with a 3TB Fusion Drive. I can't boot back into macOS from within Windows but shutting down and restarting holding the alt key is not too much of a hassle and something I can live with. I'm not often working with Win10 on my machine, so that's okay.

I hope this helps to answer a few questions and maybe it can help everyone who ran into the same or similar problems during the last few days. Let me know if you have any questions - happy to help out if I can.
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I am Back at High Sierra after a complete Reinstall to it without a Backup. Will add a new Bootcamp now, but how did you manage the recovery of the .dmg Image ? I copied the bootcamp_Vol.dmg to an external Disk as a backup before Reinstalling High Sierra. How can I use this file now ? Thx for a detailed Reply and Greets to Berlin from HH. Danke vorab !

I honestly didn't come to that step yet. I assume it should be possible to use the same program ('Windows Recovery') as before when I created the backup. Fingers crossed that will be the case... I'll let you know as soon as I found out.

 

[AxiomaticRubric]

I can confirm that this is happening on a Mac Pro 4,1 (2009) with the firmware hack to 5,1 (2010). It will not boot into the EFI screen for selecting macOS or Windows, even after a PRAM reset.

The Boot Camp Assistant app says "Boot Camp is not supported on this Mac." Windows 10 is installed on a separate SSD. However the option to select Windows is still available in Startup Disk in System Preferences. I have not attempted to boot into Windows this way.

Boot Camp was working fine in High Sierra prior to the Mojave upgrade (which otherwise appears to be functioning as expected).

This issue is not affecting only iMacs with 3TB hard drives, as stated by others on this thread. Apple can and should fix this in later versions of Mojave.

 

[neek]

I was able to mount the bootcamp.dmg and Winclone imaged that mounted volume. Imaging the BOOTCAMP_VOL is not useful. Mount the DMG inside BOOTCAMP_VOL and use Winclone to image the mounted disk image.

I've just completed a backup, reformat, and restore to move the system back to HFS+ and CoreStorage. (only 21 hours of copying). Will try to setup Bootcamp again and restore my image over the next couple of days.

I set up Bootcamp with a fresh Win 10 install and then restored my Winclone backup over the Bootcamp partition.

Success! What a pain, though.

 

[old-mac-man]

My easy solution, don't update to Mojave.

 

[robk64]

Apple today shared a support document that will be of interest to customers who own a late 2012 27-inch iMac with a 3TB hard drive and are attempting to upgrade to the macOS Mojave update.

There is an issue on this iMac model that results in the following alert when attempting to install macOS Mojave: "Installation cannot proceed with Boot Camp configured."

To fix this problem, Apple says that customers with the 2012 27-inch iMac with 3TB hard drive will need to completely remove the Boot Camp partition using Boot Camp Assistant before macOS Mojave can be installed.

After upgrading to macOS Mojave, Boot Camp will not be able to be used to install Windows on these machines. No other iMac models appear to be affected by this issue.

Article Link: Boot Camp Won't Work With macOS Mojave on 2012 27-Inch iMac With 3TB Hard Drive

I had the same thing show up on my 2013 27" iMac w/ 3TB Fusion drive. Not to be deterred, I followed the prompts to remove Windows10 via Bootcamp Assistant. Mojave installed, seemingly without a problem. Then, when I attempted to reinstall Windows10, Bootcamp Assistant would stop at the point of creating the Bootcamp partition. Ran First Aid, and at first, thought there were no problems. Upon closer inspection, I noticed there were at least 50 lines of overallocation errors. Rechecked after booting into single-user mode and running a few check and fix commands. Detected, but not fixable overallocation errors.
Luckily, I had a recent Time Machine backup. I made a bootable install USB for High Sierra, and did a complete erase of the Fusion drive, followed by installing High Sierra on the previous file format. Finished the install with vanilla settings, but with all of my usual information correct. Installed Mojave (without any warning messages) and allowed the OS to change to the APFS file format. Checked and rechecked for overallocation errors. Clean bill of health.
Finally, reinstalled Windows10 via Bootcamp Assistant. Only one issue: The Bootcamp diamond in the Windows task bar appears broken in that clicking on it doesn't automatically reboot into MacOS after you confirm you wish to do so. Instead, it gives a Windows error window stating the boot sector/drive for MacOS couldn't be found. Keeping my panic in check, I simply selected Restart from the Windows menu, and as the computer restarted, held down Alt/Option before the chime (as you would booting from Mac to Windows), and selected Macintosh HD, and it booted into Mojave.
Minor inconvenience, but everything else works.

 

[impr]

test

 

[Shoju]

Only one issue: The Bootcamp diamond in the Windows task bar appears broken in that clicking on it doesn't automatically reboot into MacOS after you confirm you wish to do so. Instead, it gives a Windows error window stating the boot sector/drive for MacOS couldn't be found. Keeping my panic in check, I simply selected Restart from the Windows menu, and as the computer restarted, held down Alt/Option before the chime (as you would booting from Mac to Windows), and selected Macintosh HD, and it booted into Mojave.
Minor inconvenience, but everything else works.

I have the exact same issue after I finally got Win10 back on my machine with Mojave. Hoping this may be fixed by Apple soon..