Bootcamp starts Windows after downloading without letting me allocate partition

Question

Bootcamp starts Windows after downloading without letting me allocate partition

Earlier today I was installing Windows using Bootcamp Assistant. I’ve followed the guide and everything is going well until my iMac restarts by itself then boots up the Windows Installation without letting me allocate a partition beforehand. when I was on the Windows Setup it shows three drives, one is my external USB harddrive which was used to install Windows, second was my iMac drive, third was a random drive that contains only 200MB of space. at this point I realized Bootcamp Assistant did not allocate any partition at all, so now I’m stuck and cannot boot up my MacOS and can only boot up Windows which I cannot install either since Bootcamp did not create an allocation.

If anyone can be of assistance, I would be really grateful.

Earlier Mac models

Posted on May 10, 2024 7:20 AM

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Answer 1

HWTech

Level 9

56,204 points

May 11, 2024 10:14 PM in response to chrisedmund06

Here is an Apple article with instructions for dealing with a missing or broken macOS installation (the first link in that article under "Question Mark" is the one you need to review:

If your Mac doesn't start up all the way - Apple Support

The easiest way forward is likely to perform a clean install of macOS by first erasing the whole physical drive (or Fusion Drive is equipped) followed by reinstalling macOS & restoring from a backup. If the partitions were modified, then it can be very difficult to fix without erasing & starting over.

How much Free storage space did you have on this Mac? Perhaps if you only barely meant the minimum amount of storage space to utilize Windows Bootcamp, then perhaps it just automatically tried to allocate it since there would be no other option. I have no idea though since I only tried using Windows Bootcamp Assistant over a decade ago.

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Answer 2

May 10, 2024 7:34 AM in response to Ozzie1910

Yes. I am aware there would be an option to allocate a partition shortly after Bootcamp Assistant is finished downloading the files from the Windows ISO, but that option didn’t appear for me and my macOS just starts the Windows Installation.

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Answer 3

May 10, 2024 7:36 AM in response to Ozzie1910

I did try unplugging the USB Drive, it instead boots up to a black screen with an error saying, “No bootable device - insert boot disk and press any key”. I also did try restarting my mac and holding down the command (alt) keyboard but it only shows Available Networks and no option to choose a drive to boot.

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Answer 4

Ozzie1910

Level 4

2,283 points

May 10, 2024 7:33 AM in response to chrisedmund06

Did you follow all the steps from the bootcamp assistance? To boot to macOS you have to unplug the usb drive

Install Windows 10 on your Mac with Boot Camp Assistant - Apple Support

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