Mac users who want to dual-boot into Windows 10 use the Boot Camp Assistant to create legitimate bootable Windows 10 USBs. Unfortunately, these drives will only work on Mac machines. To create a Windows 10 bootable USB for PCs, some extra work is necessary. I used these steps to create a Windows 10 bootable USB on a macbook pro running Catalina so that I could install Windows 10 on a Lenovo ThinkCentre m900 Tiny.
- Download the official Microsoft Windows 10 ISO. Link to download page as of July 17, 2020
- Verify your download
shasum -a 256 ~/Downloads/{filename}.iso - Download Parallels Desktop. Link to download page as of July 17, 2020
- Install Parallels to your Applications folder
- Launch Parallels
- Select 'File > New' to create a new Windows virtual machine
- Select 'Install Windows or another OS from a DVD or image file.' Click 'Continue.'
- Locate the Windows 10 ISO you downloaded from the earlier steps. Click 'Continue.'
- Unselect 'Enter Windows license key for faster installation.' Click 'Continue.'
- Select a primary use-case for Parallels and click 'Continue.' (I have NO understanding of what this does, perhaps usage analytics.)
- Select a name and location for your new Parallels virtual machine. Click 'Create.'
- Launch your new Windows 10 virtual machine.
- Possible roadblock: After creating a new Windows 10 VM, Parallels auto-launched the image for me. On this first boot, I was not able to access any files or devices such as USB drives from the host system. I shutdown the Windows 10 VM, closed Parallels, and then restarted both to continue.
- The following steps all occur inside the Windows 10 VM:
- Open 'This PC' aka 'My Computer'.
- Insert the target USB flash drive you want to be turn into a Windows 10 installer.
- Right-click the USB drive and select 'Format.'
- Format the USB drive for NTFS or FAT32 filesystems
- Download the official Microsoft Windows 10 Media Creation Tool. Link to download page as of July 17, 2020
- Launch the Media Creation Tool and accept the terms and conditions.
- Select 'Create installation media (USB flash drive, DVD, or ISO file) for another PC'.
- Select a language, edition, and architecture. Likely your Windows VM recommended options are appropriate. Click 'Next.'
- Select 'USB flash drive' and click 'Next.'
- Select your target USB drive from the list and click 'Next.'
- Finish the media creation wizard and wait for your drive to be imaged.
- After completion, eject the USB drive from your Windows 10 VM.
- Shutdown the Windows 10 VM if you are finished.
- Verify the USB drive was ejected from your MacOS host and eject it if it wasn't successfuly ejected from the Windows 10 VM.
- Insert your new USB drive into the PC where you want to install Windows 10
- Windows 10 prefers UEFI, so if your BIOS supports UEFI and Legacy, be sure that UEFI is preferred or required.
- Using the BIOS or the appropriate vendor proprietary boot menu, select your USB drive to boot from
- Follow along with the Windows 10 install wizard to complete your install