Boot Camp failed, can't 'un-partition'

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Level 1

11 points

Boot Camp failed, can't 'un-partition'

Hi all,

I am trying to install Windows 10 with Boot Camp on my iMac (see specs below), but so far I am only getting in trouble...

This is what I did:

Full backup with Time Machine on external drive
Install all updates for OS
Download Windows ISO here: https://www.microsoft.com/nl-nl/software-download/windows10ISO
Run Boot Camp with 300 GB for Windows partition

And this is what happened:

First attempt failed (I think it said something like 'couldn't install utility'), Boot Camp removed the partition back to normal
Same for the second attempt, but now Boot Camp couldn't remove the Windows partition. It instructed to restore in Disk Utility, probably as explained here: https://support.apple.com/en-us/HT209351.
In Disk Utility, I didn't see any partitions named BOOTCAMP or OSXRESERVED. I did see 'free space', but could not remove this.
The second time I looked in Disk Utility, I didn't see this free space anymore; only my HD reduced from 1 TB to 700 GB...

This is the current diskutil list:

Questions:

What can I do to remove the 'invisible and unused partition', so that I can use the full 1 TB capacity of my HD again?
If I would have the courage to try to install Windows again, what could I try to make it more successful?

I have seen posts with similar issues, bus apparently I lack the skill to translate this to a solution for my problem, so I would greatly appreciate any help...

Kind regards,

Jeroen

iMac 27″ 5K, 10.13

Posted on Sep 8, 2020 2:18 AM

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Answer 1

Top-ranking reply

Loner T

Level 9

59,513 points

Sep 10, 2020 3:27 AM in response to azwep

azwep wrote:

Yes! This allowed me to restore full disk capacity in BCA. Thanks a lot for all this sorcery!

Excellent!

Now the ultimate question: shall I dare trying to install Windows again?

Yes.

Did I do something wrong in the first place;

Perhaps not.

is there something I can try to increase the chance to succeed?

Yes. Disconnect all external peripherals, run a SMC and NVRAM Reset. Use only Keyboard/Mouse and try to install Windows.

Would installation on an external SSD be a better idea?

No. This road is fraught many a pothole.

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Answer 2

azwep Author

Level 1

11 points

Sep 9, 2020 2:29 PM in response to Loner T

The output of the 3 command lines:

Unmount of all volumes on disk0 was succesful (I had to use the command diskutil unmountDisk disk0 though)
gpt: illegal option -- i usage: gpt [-frv] [-p nparts] command [options] device ...
Finished partition map repair on disk0

In BCA I see no Remove/Restore option. Reduced disk size is unchanged.

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Answer 3

Loner T

Level 9

59,513 points

Sep 8, 2020 2:18 PM in response to azwep

Notice the large gap after GPT3.

Boot into Internet Recovery
Click on Utilities -> Terminal
Run
- diskutil unmount diskN (where N points to the 1TB disk)
- gpt -i 4 -b 1350047592 -s 603477543 -t windows /dev/diskN
- diskutil repairDisk diskN
Boot normally
Run BCA and try to click on Remove/Restore

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Answer 4

Loner T

Level 9

59,513 points

Sep 9, 2020 8:15 PM in response to azwep

Quit BC Assistant.

Try

diskutil unmount diskN (where N points to the 1TB disk)
gpt add -i 4 -b 1350047592 -s 603477543 -t windows /dev/diskN
diskutil repairDisk diskN

and then try to remove and get your disk space back.

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Answer 5

Sep 8, 2020 6:02 AM in response to azwep

I ran into that same issue having done the same thing. My method of solving it was reinstalling MacOS from the internet onto the entire drive, restoring the data, and then reinstalling Windows via Bootcamp.

It's a time-consuming option, but it worked for me; achieving the desired result is more important than time spent.

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Answer 6

azwep Author

Level 1

11 points

Sep 10, 2020 12:17 AM in response to Loner T

Yes! This allowed me to restore full disk capacity in BCA. Thanks a lot for all this sorcery!

Now the ultimate question: shall I dare trying to install Windows again? Did I do something wrong in the first place; is there something I can try to increase the chance to succeed? Would installation on an external SSD be a better idea?

Reply