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

1. If your ISO contains any single file larger than 4GB, it will not be copied to the USB.

Well, yes, my ISO files are larger than 4G

2. If the USB is USB3, this error can happen, but is inconsistent across brands of USBs.

Nope, my USB is not USB3, its USB2

3. Changing the DMG to .iso and back is not going to make a difference.

Got it.

4. Did this ISO come from Microsoft download?

Nope, I'm making the ISO file from disk installer.

What do you think? Where have I gone wrong?

As a test, can you download W7 from https://www.microsoft.com/en-us/software-download/home and try to create the USB, using the first two options in BC Assistant? We do not need to install anything yet. Please be aware that the Microsoft download can be corrupted over a wireless connection. Use a wired connection, if possible.

I am trying to install Windows 10 Enterprise using Boot Camp but I also keep getting the error "Your bootable USB drive could not be created"

I have a late 2012 Mac Mini with Yosemite.

The IT department at my company gave me the standard setup.exe and other files and folders on a flashdrive. I used Mac Disk Utility to create an ISO file from this which I have saved in my main Mac drive. When I use Boot Camp I select the ISO file and my destination disk which is a 32GB SanDisk Cruzer flashdrive which I have already formatted for MS-DOS FAT using Disk Utility. When I start the process the ISO file appears in Disk Utility so I first "Eject" it and then "Remove" it. However it keeps remounting. I get to the prompt "The drive will be erased.". This is my last chance to eject and remove the ISO file in Disk Utility which I do before continuing. The volume gets formatted and then begins to "Copying Windows Files" after which I get the "Your bootable USB drive could not be created" error. The end result is a volume named "WININSTALL" with only one file "autorun.inf"

Is there a way to prevent the ISO file from being remounted?

1. Is the USB from your IT Department still connected to your Mac when you try to create the USB installer on the 32GB SanDisk flash drive?

2. Can you move the ISO to your Documents folder rather then leaving it on your Desktop?

3. Is the 32Gb SanDisk a MBR scheme device or a GPT with a FAT partition on it? You can also post the output of Terminal diskutil list command with your USBs connected.

Loner T thanks for following up with me

1. Is the USB from your IT Department still connected to your Mac when you try to create the USB installer on the 32GB SanDisk flash drive?

I only borrowed the flash drive long enough to copy the files over to the Mac main drive. I didn't have it when I tried to install via Boot Camp.

2. Can you move the ISO to your Documents folder rather then leaving it on your Desktop?

I moved the ISO to both the Documents and Downloads folders but get the same error.

3. Is the 32Gb SanDisk a MBR scheme device or a GPT with a FAT partition on it?

When I partition the flashdrive using Disk Utility I choose the option "Master Boot Record"

I should add that I also have Parallels 10.3. When I try to create a virtual installation Parallels has no problem recognizing that it is a Windows 10 ISO, but I eventually get an error that "No boot device is available". I don't know if that may give a clue.

You can also post the output of Terminal diskutil list command with your USBs connected.

Mikes-Mac-Mini:~ Mike$ diskutil list

/dev/disk0

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *121.3 GB disk0

1: EFI EFI 209.7 MB disk0s1

2: Apple_CoreStorage 121.0 GB disk0s2

3: Apple_Boot Boot OS X 134.2 MB disk0s3

/dev/disk1

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *1.0 TB disk1

1: EFI EFI 209.7 MB disk1s1

2: Apple_CoreStorage 999.3 GB disk1s2

3: Apple_Boot Recovery HD 650.1 MB disk1s3

/dev/disk2

#: TYPE NAME SIZE IDENTIFIER

0: Apple_HFS Macintosh HD *1.1 TB disk2

Logical Volume on disk0s2, disk1s2

C0DA7F0B-28F9-46F5-AC5B-6AED8CFE4EC0

Unencrypted Fusion Drive

/dev/disk3

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *2.0 TB disk3

1: EFI EFI 209.7 MB disk3s1

2: Apple_CoreStorage 2.0 TB disk3s2

3: Apple_Boot Boot OS X 134.2 MB disk3s3

/dev/disk4

#: TYPE NAME SIZE IDENTIFIER

0: FDisk_partition_scheme *32.0 GB disk4

1: DOS_FAT_32 WININSTALL 32.0 GB disk4s1

/dev/disk5

#: TYPE NAME SIZE IDENTIFIER

0: Apple_HFS TM Backup *2.0 TB disk5

Logical Volume on disk3s2

19AF0415-7257-4569-823E-DFFA07C7041D

Unlocked Encrypted

/dev/disk6

#: TYPE NAME SIZE IDENTIFIER

0: WINDOWS 10 *4.0 GB disk6

Mikes-Mac-Mini:~ Mike$

1. You should disconnect all storage that is not needed for Windows installation. Only the USB Installer (SanDisk) and the internal disk on Mini should be connected.

2. Is disk6 your ISO?

3. Your USB seems to be correctly formatted.

4. We can manually create a USB Installer, if necessary. Do you want to try this method?

1. You should disconnect all storage that is not needed for Windows installation. Only the USB Installer (SanDisk) and the internal disk on Mini should be connected.

So I have now physically removed my TM backup disk (which was on FireWire) and my USB hub. The flashdrive is connected directly to my Mac USB3 port. I read somewhere that using USB3 might be a problem but as far as I can tell all the ports are USB3.

2. Is disk6 your ISO?

Yes, I believe so. I generated the list right after the installation failed. Right after it formats and right before it starts copying Windows files it remounts the ISO and thus causes the error. I regenerated the list below with my TM drive and USB hub physically disconnected and right before I press continue on "The drive will be erased" dialog box.

3. Your USB seems to be correctly formatted.

OK

4. We can manually create a USB Installer, if necessary. Do you want to try this method?

Yes, I would like to try to.

Thanks again.

Mikes-Mac-Mini:~ Mike$ diskutil list

/dev/disk0

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *121.3 GB disk0

1: EFI EFI 209.7 MB disk0s1

2: Apple_CoreStorage 121.0 GB disk0s2

3: Apple_Boot Boot OS X 134.2 MB disk0s3

/dev/disk1

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *1.0 TB disk1

1: EFI EFI 209.7 MB disk1s1

2: Apple_CoreStorage 999.3 GB disk1s2

3: Apple_Boot Recovery HD 650.1 MB disk1s3

/dev/disk2

#: TYPE NAME SIZE IDENTIFIER

0: Apple_HFS Macintosh HD *1.1 TB disk2

Logical Volume on disk0s2, disk1s2

C0DA7F0B-28F9-46F5-AC5B-6AED8CFE4EC0

Unencrypted Fusion Drive

/dev/disk3

#: TYPE NAME SIZE IDENTIFIER

0: FDisk_partition_scheme *32.0 GB disk3

1: DOS_FAT_32 UNTITLED 1 32.0 GB disk3s1

Mikes-Mac-Mini:~ Mike$

Loner T, thanks for all the help. I only need Windows 10 for PowerPoint since the Mac version continually crashes on me so I assume it will be fast enough. I assume that the Win10 partition would also have been installed on the slow HDD part of the Fusion Drive even if I was able to do it through the normal automated Boot Camp installation. I have Parallels 10 but I haven't been successful installing it in a VM either. I assume that there is some step that I missed when creating the ISO file in Disk Utility.

The HDD part is very reasonable. If your HDD is 7200rpm, it will be a bit better, but I know Apple started using 5400rpm HDDs to avoid heat issues and subsequent failures. You are correct that BCA would also use the HDD part for Windows on a Fusion drive by design.

Once the USB is built, there is one more step to make it bootable. Post back once you have the USB built, and I can provide steps.

Loner T, I just got back to trying to install Win10 on my Mac. I followed the instructions you gave me and my USB root directory looks familiar to the example you provided. The only thing that was different is that there was no zip file. BCA only allowed me to download the support software directly to the USB (not Mac drive) and the $WinPEDriver$ folder, the Bootcamp folder and the AutoUnattend.xml file were all directly copied to the root of the USB.

Can you give me the instructions you mentioned about making the USB bootable and what else I need to do to start the installation?

Thanks again

Mike

I should mention that instead of using the 32Gb USB stick, I have switched to an 8Gb SanDisk (disk 4 below)

Mikes-Mac-Mini:~ Mike$ diskutil list

/dev/disk0

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *1.0 TB disk0

1: EFI EFI 209.7 MB disk0s1

2: Apple_CoreStorage 999.3 GB disk0s2

3: Apple_Boot Recovery HD 650.1 MB disk0s3

/dev/disk1

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *121.3 GB disk1

1: EFI EFI 209.7 MB disk1s1

2: Apple_CoreStorage 121.0 GB disk1s2

3: Apple_Boot Boot OS X 134.2 MB disk1s3

/dev/disk2

#: TYPE NAME SIZE IDENTIFIER

0: Apple_HFS Macintosh HD *1.1 TB disk2

Logical Volume on disk1s2, disk0s2

C0DA7F0B-28F9-46F5-AC5B-6AED8CFE4EC0

Unencrypted Fusion Drive

/dev/disk3

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *2.0 TB disk3

1: EFI EFI 209.7 MB disk3s1

2: Apple_CoreStorage 2.0 TB disk3s2

3: Apple_Boot Boot OS X 134.2 MB disk3s3

/dev/disk4

#: TYPE NAME SIZE IDENTIFIER

0: FDisk_partition_scheme *7.8 GB disk4

1: DOS_FAT_32 Win10E 7.8 GB disk4s1

/dev/disk5

#: TYPE NAME SIZE IDENTIFIER

0: Apple_HFS TM Backup *2.0 TB disk5

Logical Volume on disk3s2

19AF0415-7257-4569-823E-DFFA07C7041D

Unlocked Encrypted

/dev/disk6

#: TYPE NAME SIZE IDENTIFIER

0: Boot Camp *2.8 GB disk6

Mikes-Mac-Mini:~ Mike$ sudo fdisk /dev/disk4

Password:

Disk: /dev/disk4 geometry: 947/255/63 [15223808 sectors]

Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: 0B 1023 254 63 - 1023 254 63 [ 2 - 15223806] Win95 FAT-32

2: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

3: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

Mikes-Mac-Mini:~ Mike$

Please ignore the i386 MBR error, but not any others in the following steps.

sudo fdisk -e /dev/disk4

p

flag 1

p

w

y

Now BC Assistant, and click only on the 'Install...' option and partition your drive as necessary and install Windows. If you see any error messages, please post back.

Not sure if this is an error but after typing w I get "Device could not be accessed exclusively. A reboot will be needed for changes to take effect. OK? [n] "

Mikes-Mac-Mini:~ Mike$ sudo fdisk -e /dev/disk4

Password:

fdisk: could not open MBR file /usr/standalone/i386/boot0: No such file or directory

Enter 'help' for information

fdisk: 1> p

Disk: /dev/disk4 geometry: 947/255/63 [15223808 sectors]

Offset: 0 Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: 0B 1023 254 63 - 1023 254 63 [ 2 - 15223806] Win95 FAT-32

2: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

3: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

fdisk: 1> flag 1

Partition 1 marked active.

fdisk:*1> p

Disk: /dev/disk4 geometry: 947/255/63 [15223808 sectors]

Offset: 0 Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

*1: 0B 1023 254 63 - 1023 254 63 [ 2 - 15223806] Win95 FAT-32

2: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

3: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

fdisk:*1> w

Device could not be accessed exclusively.

A reboot will be needed for changes to take effect. OK? [n]

Type 'y' and continue. Type 'q', if necessary to exit from Fdisk. Eject the USB, connect it again, and check the output of

sudo fdisk /dev/disk0

If it shows the asterisk in the first entry with 0B, you are good to proceed further.

I started BCA and it asked me how large I wanted to create the partition, I chose 100GB. After some time I got a black screen with a boot error. I unplugeed the.USB stick and tried a hard power reset of Mac and I get the error "No bootable device -- Insert boot disk and press any key". So I can't boot my Mac now. I did a TM backup right before I started so I shouldn't have lost any data but I don't know what to do to get the Mac to boot now. I am posting using my iPad.