This should be a trivial one; unfortunately, it isn't. I've been trying to create a bootable USB stick for Windows 10. The bootcamp tool seems easy to use, but it always stops with the following message:

Your bootable USB drive could not be created.
There is not enough space available on the disk.

I've tried with too different USB sticks, a KINGSTON USB 2.0 16Gb stick and a Corsair USB 3.0 32Gb stick. I first tried to do this on MacOS 10.12, no luck, and then took this experience as an incentive to upgrade to MacOS 10.14, yielding the same result.

The Windows version I downloaded from Microsoft is the newest October update. The filename is:


The bootcamp tool doesn't allow any customization of the process, I don't think there is anything I could do different. I have difficulties to believe that bootcamp is just broken.

I've also tried to create the USB stick both with dd and Etcher, both yielding no error, but the stick wasn't bootable in the end. Etcher even warned me about this and suggested to use bootcamp instead. Instructions how to make the USB stick bootable would be welcome.

  • Will this be used to install Windows on a Mac? If so, which model Mac? Dec 14, 2018 at 0:07
  • Yes, a MacBook Air 2014 Dec 14, 2018 at 0:12
  • What if you reformat it as exFAT or some such? I know Boot Camp does reformat the thumb drive as it sets it up for a Windows install but it's a quick step. Also do you have an 8GB stick to try? Dec 14, 2018 at 0:15
  • @Steve Chambers: The Boot Camp Utility formats the USB flash drive as FAT32. However, there is one file that needs to be copied from the ISO to the USB flash drive that is over the 4 GB limit. If you mount the ISO, you find that /sources/install.wim is 4.4 GB in size. Dec 14, 2018 at 0:27
  • 2
    I did post an answer to your question. See Boot Camp Assistant fails to create the USB installer from the Windows 10 October 2018 Update. I would post the answer here, but I know the people running AD do not like duplicate answers. Dec 19, 2018 at 10:42

1 Answer 1


I found a guy who told a work around how to create, in the "right way", a USB bootable for both (on bootcamp and windows machine). The "Answer 1" works for me. I hope it helps you too.

Boot Camp Assistant fails to create the USB installer from the Windows 10 October 2018 Update

See ya!

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