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Using Bootcamp on a Macbook Air 2013 (Mojave) to install Windows 10 on a partition (as I have done several times in the past) I found the process no longer works!

  • Bootcamp requires an MS-DOS(FAT) USB stick and partition
  • Windows 10 1909 (latest and only version available from Microsoft) contains files larger than 4GB, and is therefore not compatible with MS-DOS(FAT) drive partitions
  • Windows 10 October 2018 ISO is no longer available from Microsoft or any reputable site that I can find
  • The Bootcamp software itself cannot download windows, giving a "not enough disk space" error, despite disk space being available, because of the FAT32 file size limit issue listed above.

I have tried using ExFat on the USB stick, which works up to a point, but is not able to install Windows 10 onto the Mac, presumably because the partition created by bootcamp is also FAT format.

Does anyone know of a reliable source for Windows October 2018 ISO? Or is anyone aware of an update to bootcamp which fixes this problem?

Leon
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  • Boot Camp Assistant should format & copy the iso to USB, don't do it manually - https://support.apple.com/HT201468 – Tetsujin Apr 22 '20 at 08:46
  • Indeed. But it can't for the reasons I mentioned above. Bootcamp gives an error while trying to copy the ISO onto the USB stick because the USB is not compatible with files over 4GB and the latest version of Windows exceeds that limit – Leon Apr 22 '20 at 09:17
  • Are you sure you're downloading only the ISO you need for your platform, and not a 64-bit/32-bit combo? Last time I had to download a Windows 10 ISO from Microsoft, I ended up with a 5+GB file, that contained both 64- and 32-bit versions, when all I was asking for was the 64-bit one. –  Apr 22 '20 at 09:23
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    Boot Camp shouldn't copy the ISO, it should copy the contents. If, for some reason, it's not doing that, then mount the ISO on the Mac or a Windows PC & manually copy the contents to the USB. As Didier says, if it contains both 32 & 64, just copy the 64. You're unfortunately stuck with one of the Macs that can't install directly by accessing the ISO online. That changed in about 2015. – Tetsujin Apr 22 '20 at 09:30
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    If the install.wim itself is larger than 4GB, see https://superuser.com/a/1345687/347380 – Tetsujin Apr 22 '20 at 09:34
  • To add to the debate: https://www.tenforums.com/general-support/144946-windows-10-1909-iso-has-different-sizes.html. Apparently, depending on the format you download, the file can indeed be just under, or largely exceed, 4GB in size, and that changes a lot of things. (and that's just for a 64-bit version; 32-bit are usually smaller, regardless of the file being .esd or .wim) –  Apr 22 '20 at 09:36
  • Using 64bit only WIN10_1909 - ISO size 5.3GB - mounted ISO contains individual files larger than 4GB – Leon Apr 22 '20 at 09:43
  • @Tetsujin I can mount the ISO and copy the files, but one file will not copy as it exceeds 4GB – Leon Apr 22 '20 at 09:45
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    Did you read my link? – Tetsujin Apr 22 '20 at 09:45
  • @Tetsujin i did try exactly that BUT the partition Bootcamp created was also FAT format, and thus could not install windows from the USB! – Leon Apr 22 '20 at 09:51
  • I have the same problem as Farzad mentions in his comment here : https://superuser.com/a/626375/1166767 – Leon Apr 22 '20 at 09:53
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    So.. you read it but you didn't do what it said... – Tetsujin Apr 22 '20 at 09:55
  • @Tetsujin I have done exactly that but it didn't work. Windows install hangs. It seems you cannot install the latest version of Windows onto the partition Bootcamp creates – Leon Apr 22 '20 at 10:08
  • .. removing partition, trying again using the ExFat USB method... – Leon Apr 22 '20 at 10:16
  • No joy. I did get a lot further with the method described by @Tetsujin ... in the end the partition was created and windows setup almost completed, but at a certain point it would always hang. I'll post an answer with my findings in case someone else can get further – Leon Apr 22 '20 at 14:05
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    "Windows 10 October 2018 ISO is no longer available from Microsoft" - This certainly isn't true, the existing [question](https://superuser.com/questions/1108085/where-can-i-get-a-clean-iso-of-a-specific-build-of-windows-10) on this subject, provides more than one option to download it directly from Microsoft. Now the links certainly appear on a third-party website, but all those options, are absolutely getting the ISO directly from Microsoft. – Ramhound Apr 22 '20 at 14:42

2 Answers2

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I installed it today!

I was getting the "not enough disk space" until I updated to OS Catalina, then used the 1909 64x iso and a standard empty 16gb usb drive.

Bootcamp formatted my usb drive during the process.

I had the first and last box checked on the bootcamp installer and used the Activity Moniter App>Disk Tab>Bootcamp Installer to make sure files were still being written, as it sometimes appeared frozen.

Took a couple hours, 130gb partition. Macbook pro late 2013 model

I used: https://www.google.com/amp/s/www.imore.com/how-install-windows-your-mac-boot-camp%3famp and https://support.apple.com/en-ca/HT201468

I hope this helps!

Mitch
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I wasn't able to get Windows 10 1909 installed successfully, but posting an answer here as it might work for someone else :

@Tetsujin drew my attention to this post https://superuser.com/a/1345687/1166767 - following the instructions exactly worked on about the 3rd attempt! This allowed me to create a functioning USB stick and begin the Windows install process on a partition.

The install would then freeze at various points, as described here https://teching.nl/2017/03/bootcamp-windows-10-stuck-on-logo/

Unfortunately the install would not complete. This may be a separate bug not related to my initial question but related to my specific Macbook Air 2013, as described by other users here https://discussions.apple.com/thread/8350388

I hope one of these solutions can help a future user.

Leon
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    Apple's support of exFAT is spotty, at best. They and Microsoft (and others) can get their stories straight when it comes to default cluster size, among other things. Have you tried to install a 32-bit version instead? I know it's not ideal, especially if you've got plenty of RAM on your Mac, but 32-bit ISOs are usually more manageable than 64-bit, due to the fact that the machine they are destined to also have lower specs. Worth a try. –  Apr 22 '20 at 14:37
  • so, currently, it's still not possible to dual boot with Windows 10 ? I've also tried, and spent a week now, everything in the book - following instructions. I even, with a manual method, got to boot to windows install, but the Windows install failed with the dreaded "windows could not prepare the computer to boot into the next phase of installation" error. It's hopeless. – MC9000 May 05 '21 at 01:13