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bootcamp windows 10 does not format correct

Have tried to install windows10 50 times, every time i get the error under the installation "The disk and partition called in the automatic answerfiles <ImageInstall>- setup was not found. Check the setup calls the right partition and disk in the file and restart installation" or i get this error "Partition is formatet in NTFS have to be in FAT32, format again with the correct format" and in this case it is the little partition almost 400mb.

Help needed, I can install with Parallel Desktop or on an external disk with "Win2USB" but not what i want.

My iMac is 2017 retina 5k 27" running os x 10.12.6. I have tried newer os x but with same bad result. I have called support on the phone many times but even I have paied for the ekstra support I get no help.


Thank you in advance.

Frank

iMac with Retina 5K display, macOS 10.12

Posted on Jan 4, 2020 5:38 AM

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Question marked as Best reply

Posted on Jan 4, 2020 8:52 PM

Consider the following option


  • On your 3TB external disk, create two additional partitions - 1TB and 64GB
  • Format the 1TB as Apple HFS+ and use it to backup your macOS partition via Time Machine
  • Format the 64GB as Apple HFS+ and
    • Boot into Local Recovery using Command+R
    • Install macOS Sierra (10.12.6) on this 64GB partition (see How to reinstall macOS from macOS Recovery - Apple Support for reference)
    • Boot from this 64GB partition and verify that you have a Recovery HD associated with this partition. It should be located on the 3TB disk
    • Now you have a full external boot, without any Internet Recovery dependency
    • Boot from this 64GB partition
    • Once booted, we can rebuild the Fusion drive, if necessary manually
  • macOS Sierra supports W10
  • Once you have macOS Sierra on the external disk and Fusion drive has been rebuilt, re-install macOS Sierra on the Fusion drive, but do not restore your TM backup yet.
  • Do not upgrade to Mojave or Catalina, because they will bring new issues
  • Be aware that W10 1909 ISO may not work properly on macOS Sierra due to a large-than-4GB install.wim file
  • Once W10 is installed, then you can restore your TM backup and verify that both OSes work properly.
14 replies
Question marked as Best reply

Jan 4, 2020 8:52 PM in response to Stampe169

Consider the following option


  • On your 3TB external disk, create two additional partitions - 1TB and 64GB
  • Format the 1TB as Apple HFS+ and use it to backup your macOS partition via Time Machine
  • Format the 64GB as Apple HFS+ and
    • Boot into Local Recovery using Command+R
    • Install macOS Sierra (10.12.6) on this 64GB partition (see How to reinstall macOS from macOS Recovery - Apple Support for reference)
    • Boot from this 64GB partition and verify that you have a Recovery HD associated with this partition. It should be located on the 3TB disk
    • Now you have a full external boot, without any Internet Recovery dependency
    • Boot from this 64GB partition
    • Once booted, we can rebuild the Fusion drive, if necessary manually
  • macOS Sierra supports W10
  • Once you have macOS Sierra on the external disk and Fusion drive has been rebuilt, re-install macOS Sierra on the Fusion drive, but do not restore your TM backup yet.
  • Do not upgrade to Mojave or Catalina, because they will bring new issues
  • Be aware that W10 1909 ISO may not work properly on macOS Sierra due to a large-than-4GB install.wim file
  • Once W10 is installed, then you can restore your TM backup and verify that both OSes work properly.

Jan 4, 2020 6:25 PM in response to Stampe169

Your current disk layout, known as a split Fusion drive, is not supported by BC Assistant.


  • Is there a specific reason that you have the Fusion drive split?
  • You have two Macintosh HD partitions, one on each of the SSD and HDD part of the Fusion drive. Do you have two different version of macOS (or a different set of files) on each of these installations?
  • Which of the two installations is critical for you? To be able to use BCA, the Fusion drive must be reconstituted. See How to fix a split Fusion Drive - Apple Support for reference.

Jan 4, 2020 6:25 PM in response to Stampe169

Your current disk layout, known as a split Fusion drive, is not supported by BC Assistant.


  • Is there a specific reason that you have the Fusion drive split?
  • You have two Macintosh HD partitions, one on each of the SSD and HDD part of the Fusion drive. Do you have two different version of macOS (or a different set of files) on each of these installations?
  • Which of the two installations is critical for you? To be able to use BCA, the Fusion drive must be reconstituted. See How to fix a split Fusion Drive - Apple Support for reference.


Jan 4, 2020 7:50 AM in response to Stampe169

The <ImageInstall> tag is populated by BC Assistant using information from your running system. This doe into work if your W10 ISO was corrupted during the download process. If you have a split Fusion drive, it can also lead to installation issues.


There are three partitions used for Windows installation on your iMac.


  • EFI (or ESP) which should be FAT32 and stay FAT32
  • OSXRESERVED which is created by BC Assistant and contains the BC drivers and Windows ISO contents. This is normally FAT32 (macOS High Sierra or older) or exFAT (macOS Mojave or later)
  • designated Windows destination partition which can be FAT32 or NTFS. Newer macOS versions (macOS Mojave and later) format it as NTFS, which eliminates the manual step fo selecting and formatting this partition


From macOS Terminal, can you post the output of


diskutil list


Where did the W10 ISO come from? What is the name and mD5sum of the ISO file?

Jan 4, 2020 5:24 PM in response to Loner T

Hi, I started with my old version of w10 back from 2015 and since tried version 18xx 1903 1909, they all wokr well if i put them on a dvd and install to a PC, I don't know the checksum md5 because i never been looking for it, i read another place on the web after lots of googling that it could be the iso file was too big so it should be running throug a progtam that was splitting files to less than 2gb and then put it together, did not help. I have a fusion drive, but i have split it, but the result is the same if is running fusion or not.

Jan 4, 2020 7:32 PM in response to Loner T

First i would use it for recover, but have tried with split and no split but with same 2 results, i only have os x 10.12.6 but have a recovery partition because it is faster than using the web and i don’t trust the web to give me the version i want. I will try again when i get home and start with the fix, i will return in almost 11 hours.

Jan 4, 2020 10:58 PM in response to Loner T

Thank you for the info, I can tell my 2TB external drive has a bootable version of sierra, i made a clone with the CCC and i can boot from that drive and it also have a recovery partition, but my 3TBdisk is off limit, all my wierd installationsfiles for mac and pc are saved there, but i will work with it when i come home, hope it works, i have used lots of hours fighting with that and spend 8 hours on the phone with support without any luck, but guess they dont care even when you have paied ekstra for 3 years support.

Jan 5, 2020 9:06 AM in response to Loner T

Hi, I don’t know exactly whats different from what i did in the past and the instructions you gave me, but now it have finised the installation of win10 and bootcamp drivers installed too, the only differens i can think of is the partitioning of the external drive and install the os from that recovery part, but works now, so thank you very much for your help.

bootcamp windows 10 does not format correct

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