To troubleshoot an issue with Windows 10 (especially boot-related issues), it can be handy to boot into Windows 10 not installed on a Boot Camp partition. It is relatively straightforward to create a bootable USB Flash drive to boot to the Windows 10 installer and open up a DOS prompt for troubleshooting.
Using Apple's Disk Utility under Mac OS X 10.1 i could see the drive, but it wouldn't mount. I followed the hint above, as specified, using the default block-size as 512, and got 10GB throughput/per hour, which left me with a recovery.dmg after approx 2.25 hours (admittedly, and thankfully, a smaller drive). Older Mac OS X release can use Disk Utility to burn ISO and other images as well, but modern versions of Disk Utility have lost that capability. Fortunately, the dd tool can burn ISO images from the command line as well as write an image to a USB drive. I tried to make bootable linux USB drive with SDHC 8Gb flash card on my MacBook with dd command according to this guide. Also I googled a lot and found out that was the same issue in the past and no solution. So, step by step what was done: mount flash and check it with diskutil list command I got something like this.
All the preparation is done in macOS on the Mac that is having an issue booting Windows. It is important to use this Mac since it will be used to identify the correct Windows drivers.
The USB Flash drive must be formatted as exFAT.
Open Boot Camp Assistant in the Utilities folder and download the current Windows Support Software from the “Action” dropdown in the menu bar. Save the Windows Support Software to your desktop or other location. Do not save directly to the USB Flash Drive.
Download the current install media from the Microsoft website. Windows will not be installed, but the install media will give access to the command line tools in Windows. Select the version of Windows that is closest to the version of Windows installed on the Mac (Windows 8, Windows 10). It does not matter what edition of Windows is used, since Windows is not going to be installed.
To create the USB Flash drive, follow these steps:
Once the flash drive has been created, it should look like this:
The $WinPEDriver$ folder is important because it contains the drivers for Windows to boot successfully from the USB flash drive and the hardware on that Mac.
To inject the drivers, the Mac must be booted from the USB flash drive.
If Windows does not boot from the USB flash drive after showing the Windows logo, you may have to run the following command to tell the firmware to boot the Windows installer from the USB flash drive. This has been observed on the late-2014 Mac Mini but may affect other models as well. To set the variable:
sudo nvram InstallWindowsUEFI=1
Insert the USB flash drive if it is not inserted, reboot, and select the EFI volume from the startup selector.
Note: the InstallWindowsUEFI variable is cleared at each reboot, so you will need to set it again if you do not select the USB Flash Drive.
When Windows 10 starts up, it will prompt for installation of Windows 10. To open a DOS window, press fn-Shift-F10 (or just shift-F10) or click Repair Computer->Troubleshoot->Command Prompt (if available).
Once in the command prompt, there are usually 3 drive letters available: X, C, and D.
Within the Windows command prompt, you can run utilities on the Boot Camp partition.
These advanced steps are primarily for system administrators and others who are familiar with the command line. You don't need a bootable installer to upgrade macOS or reinstall macOS, but it can be useful when you want to install on multiple computers without downloading the installer each time.
MyVolumein these commands with the name of your volume.
* If your Mac is using macOS Sierra or earlier, include the
--applicationpath argument and installer path, similar to the way this is done in the command for El Capitan.
After typing the command:
Yto confirm that you want to erase the volume, then press Return. Terminal shows the progress as the volume is erased.
Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:
A bootable installer doesn't download macOS from the internet, but it does require an internet connection to get firmware and other information specific to the Mac model.
For information about the
createinstallmedia command and the arguments you can use with it, make sure that the macOS installer is in your Applications folder, then enter the appropriate path in Terminal: