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The selected disk has an MBR partition table.
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This successfully enters the Windows setup, but when I progress through all of the steps, at the step where I select which partition to install Windows on, it tells me that "Windows cannot be installed to this disk. Next, I try to instead start up with the EFI option.
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It brings me back to my original problem with the black screen and the "no bootable device" message. The options are "Macintosh HD", "Windows", and "EFI". So next I try to circumvent this issue by restarting, holding Alt/Option, and it brings up the boot order page. HOWEVER, when the iMac restarts, it shows the normal white screen, and then it shows a black screen that says "No bootable device - insert boot disk and press any key". The Windows 10 Setup screen should have showed up on the iMac Screen after restarting. I have installed Bootcamp on my Macbook Pro before so I know what should have come up. It installed the ISO image onto my DataTraveler 16GB flash drive, along with the support files. I went through the Bootcamp assistant, and it all went smoothly. I wanted to dual boot my 1TB hard drive (not SSD) to run Bootcamp Windows 10 Pro and MacOS. I have an iMac 27" Late 2012 which runs MacOS Mojave.
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