My friend had an issue with her windows laptop and she asked me to help. The laptop cannot boot properly anymore so I wanted to reinstall Windows from usb. I tried to restore but it didn't work. Since I have a Mac, most tools to create a bootable USB don't work.
I couldn't use Boot Camp Assist (as most howtos suggest) because it didn't show the option to "burn" an USB on my system and I didn't want to install Xcode hoping to change that. I "burnt" my usb using dd but I couldn't convince the laptop to boot from it. So after some more research I found unetbootin and an howto that suggests to erase the usb and formatting it using fat32 and then "burn" the iso using unetbootin. It ALMOST worked - windows installer starts but then complains about "cannot open d:\sources\install.wim 0x8007000d" (hope this reference helps other come to this question) searching for this I found that this file is bigger than 4GB so FAT32 is not an option. I reformatted the usb on Mac using exFAT and reinstalled the iso using unetbootin - but still no solution When I format the usb with FAT32, I can see a UEFI entry pressing F12 on the Dell during startup - but now that option is not there. I can choose USB in the legacy menu but I just get to a blinking cursor. Ideas? thanks!
You have to use the Windows 10 April Update 2018 version of the
.iso found here: https://www.microsoft.com/en-ca/software-download/windows10ISO
Then, continue to format your drive as FAT32 and copy files as per: https://appleinsider.com/articles/18/01/18/tips-how-to-make-windows-10-install-media-on-macos-high-sierra
You will need FAT32 as UEFI boot requires it.
Rationale: The ISO for October 2018 has an
install.wim is over the 4gb limit of FAT32 and April 2018's is not. I've scoured the internet for the past hour and this is the only solution I've found so far.
If you can use Ubuntu either via another machine or a simple Bootable USB version (I only had a Mac and a Windowless PC - and nothing I did on Mac properly allowed the Windows boot drive to actually launch from BIOS), once you get the Windows .ISO onto Ubuntu you can use WoeUSB (this tutorial helped me a lot) to make a nice bootable Windows USB.
I used it to get Windows installed on a new PC.
Since have seen lots of people struggling with making Bootable Windows drives via Mac / Boot Camp Assistant and with UNetbootin (which seems un-updated in almost a year and isn't working with Mojave it seems) I figured would offer this option since it worked and is all free alternative when the Mac just isn't getting a proper bootable Windows installer.
You can do it with: https://unetbootin.github.io/
Install it, download the Windows 10 ISO here: https://www.microsoft.com/en-ca/software-download/windows10ISO
Start Unetbootin in, select radio button DiskImage select the right ISO file. Choose the correct USB media and click ok.
Does the PC boot using UEFI or legacy MBR? If the PC can be configured to boot using UEFI, then it is easy to make a bootable Windows USB installer. Erase the USB drive with a FAT32 partition. I don't recall if it matters whether it is a MBR partition or GUID partition.
Double-click a Windows installer .iso file to mount it on macOS. Then select all the files on the mounted volume and copy them to the USB drive. As long as the Windows installer doesn't include a file larger than 4GB this should work. I've used this multiple times for Win7 and older versions of Win10. I haven't tried this with the latest version of Win10.
If the Win10 installer has a 4GB or larger file, then you may be able to format the drive as exFAT and use the rEFInd boot manager to boot the USB drive.
Edit: This only works for installing Windows on a non-Mac computer. Otherwise you need to use Bootcamp Assistant to create the bootable Win10 installer for a Mac here.
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