Boot Camp 'Your bootable USB drive could not be created' error

If the install.wim or boot.wim file on the ISO is larger than 4GB, then BCA does not copy the file to the USB since FAT32 file size limit is 4GB. This is usually the case when you have mixed 32-bit/64-bit ISO or multiple Windows variants in a single WIM file.

As a test Download Windows 10 Disc Image (ISO File) and use BCA and check if it works.

Yup, the answer is that the iso is over 4gb, which is more than fat32 on my USB allows for a single file.

USBs can have boot ability limitations. I use a SanDisk Cruzer USB2 flash drive and have used it on several Minis and MBPs to install Windows. Lexar sticks also work very well. Kingston Data Traveler ones are hit and miss. If you want to attempt a non-VM installation, please post back.

The USB ports on the Mini will support USB2 and USB3 devices. If your USB shows up under the Superspeed bus, it is a USB3, otherwise it is a USB2.

deanfromstratford wrote:

If this post is read by anyone I hope it saves you time. If you get this error. Uncheck the the top option in bootcamp. You will then get the meaningful error message is that you need to reformat your usb/drive. Do that, re-check the first option in bootcamp and then continue. This removed the problem for me. THE USB DRIVE needs to be a FAT file! Got it? I wish this could have been displayed by Apple and saved me a few faff hours.

It is. From https://help.apple.com/bootcamp/assistant/6.0/#/bcmp09f5f773 ,

Install Windows on your Mac using a USB hard drive or flash drive

Depending on the model of your Mac, you might need an external USB drive to install Windows (you’re asked for one when you prepare your Mac for Windows if it’s required).

To find out which versions of Windows your Mac supports, see the Apple Support article System requirements to install Windows on your Mac using Boot Camp.

What you need

• The keyboard and mouse or trackpad that came with your Mac. (If they aren’t available, use a USB keyboard and mouse.)
• An 8 GB or larger external USB drive (a hard drive or a flash drive), formatted as MS-DOS (FAT).To format an external USB drive as MS-DOS (FAT), use Disk Utility, located in Launchpad > Other.
• A Windows ISO image (a disk image that contains the entire contents of a DVD) downloaded from Microsoft, or both a Windows full-install installation disc (not the upgrade version of Windows) and a built-in disc drive or compatible external optical drive.To download Windows ISO images, see Microsoft Software Downloads.
• At least 32 GB of free space on an internal hard drive.

in another thread following solution was given:

"A very simple solution: make sure the ISO file is not mounted when running the Boot Camp Assistant!"

Thanks. I was putting the fact that I couldn't get Boot Camp Assistant to put Windows 7 onto an 8Gb flash drive down to Disk Utility on Sierra. After numerous failed attempts, I tried your solution. Things seem to be chugging along just fine now.

Strange thing is that I didn't even know the ISO file had been mounted until I saw your post. Thanks again.

I don't get the error any more. I just plugged in my 8 GB USB drive (Not containing the iso file or anything else, FAT 32 formatted). Checked the first box, installing windows 7 with an iso file. Chosed the path to the iso file, which was not on the USB drive but in my download folder. Even though is says it will format the data on the drive chosen, it formatted my USB and is now copying the windows files to my USB.

Hope this helps.

1. Your Mini has a 1TB Fusion drive, so the Windows installation will be installed on the HDD part, which going to be slow.

2. Erase/Format your USB SanDisk 32GB.

3. Copy the contents of the Windows USB drive including the setup.exe that you have from your IT department to the root of the USB.

4. Run BCA and only click on Download Software...

5. Create a directory/folder on your OSX side which contains the zip or the expanded .zip contents.

6. Copy the $WinPEDriver$ folder to the root of the SanDisk.

7. Copy the Bootcamp folder to the root of the SanDisk.

8. Copy the AutoUnattend.xml to the root of the USB.

Your USB should look similar to the following.

1. Please ensure that your USB is a USB2 flash drive.

2. The NVRAM has been set for Windows and multiple reboots that Windows needs. Please run the following two procedures and then try the Alt/Option key after reboot.

Resetting the System Management Controller (SMC) on your Mac - Apple Support

How to Reset NVRAM on your Mac - Apple Support

To add some additional information to my above post. I'm trying to install windows 10 off of a purchased USB home version. My laptop is a mid 2012 macbook pro. The error message i'm receiving says "Your Bootable USB drive could not be......" followed by "Boot Camp only supports Windows 7 or later installation on this platform. Please use an ISO file for Windows 7 or later installation."

I followed the apple guide found here: Create an ISO image for Boot Camp from Windows installation media - Apple Support to make my USB file into an ISO which is what i've been trying to use in bootcamp. The file is currently sitting in my documents and is approximately 15gbs, The USB i'm using is a 16gb USB. As soon as i choose my ISO image and press continue in the 3rd screen on bootcamp, i receive the error.

1. Can you post the MD5sum of your ISO file?

2. 2015 and later Macs do not use a USB installer, but use an internal partition called OSXRESERVED. Please see https://help.apple.com/bootcamp/assistant/6.0/#/bcmp173b3bf2 for reference.

There must be 10 replies all saying the same thing: "don't have the iso on the usb to begin with".

Dooooy! Yeah, it still doesn't work genius, even taking the iso from the hard drive.

Are you running into issues with the Windows Installer creation?

No, it won't copy files to my fat 32 formated 16gb USB drive. It gives me the error, not enough space on drive

Thanks, yeah I have been using a downloaded iso file. How should the USB be formatted?