Bootcamp install messed up partition or ???

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Level 1

24 points

Bootcamp install messed up partition or ???

I was running bootcamp on my Macbook Air early 2015 (MBA 7.2) but needed more space. So I deleted bootcamp, recovered the free space, upgraded from Mojave to Monterey including the latest updates (last available updates), and upgraded my MBA with a 1TB m.2 NVME SSD. No problem.

Then started Bootcamp Assistent and made a 250 GB Mac partition and a 750 GB W10 partition. Inserted a USD drive with a W10 ISO file and started the process.

That went OL following all steps until the W10 installer question came: where do you want to install windows. It would not let me install it on the W10 partition or format that partition. But I could get it onto

a new Bootcamp partition of 40 GB. I thought, why not, maybe it is supposed to go like this and you can always enlarge that partition later. So installed windows there, all nice and good. Both MAC and Windows work a charm.

However, when I tried to add another partition on the Windows drive to separate W10 and Data, something strange showed up which definitely (as far as I can remember) did not happen 5 years ago with Mojave.

This is the screenshot from Windows Disk Management

From left to right, showed from left to right a 200 MB EFI System Partition, an 891 GB Primary Partition, and the 40 GB Bootcamp mentioning Boot, PageFile, Crash Dump, Basic Data Partition (presumably this is where W10 OS now is). The Bootcamp partition is completely at the end of the drive.

From this, it looks Windows Disk Management has complete access to 930 GB, which is most of the drive, with only 70 GB hidden, which is presumably where the Apple OS is. Definitely not close to the planned 250 GB and 750 GB partition I tried to initiate.

Switching to the Mac OS, Disk Utility showed the following:

Going a step deeper into the container:

And the bootcamp partition:

Looking at Disk Utility, it looks like that partitions are split between 957 GB for Robo (my Mac Account) including the Mac OS and the rest free space and the 42 GB Bootcamp which has the Windows stuff.

This does not make sense to me and definitely is not how it looked with the old original 128 GB Apple drive installed. Can anybody explain this to me please?

Now both Apple and Windows were just installed, did not put data or extra software there, so I can easily delete the Bootcamp and start again, but I would like to understand what happened.

MacBook Air 13″, macOS 12.7

Posted on Mar 13, 2025 2:26 AM

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Answer 1

HWTech

Level 9

63,566 points

Mar 13, 2025 3:00 PM in response to RoboMcd

I only ever used Windows Bootcamp once for a short time decades ago so I don't recall how Windows treated the system. In your picture of Windows Disk Management screen, just because it shows the macOS partition as healthy doesn't mean Windows can use it in any way except to reformat it because it doesn't show its file system or assign it a drive letter.

How did you create that original 750GB partition you intended to use for Windows? Did you first install macOS to the whole physical SSD so there was just a single partition (aka APFS Container) for macOS....then used Bootcamp Assistant to resize the partition to create the Windows partition?

FYI, to get a true look at the drive layout you need to use the command line in macOS since Disk Utility will hide things from the user....it appears Windows may be doing the same in Disk Management as well, but macOS is showing the missing storage as being part of macOS which is weird. Here is the macOS command to see the layout of the internal drive:

diskutil  list  internal

macOS is finicky when trying to remove Windows & reclaim the storage used by other operating systems. You can try using Bootcamp Assistant to remove Windows which should delete the Windows partition and merge it back into the partition from which it was split. Unfortunately some people find that these other partitions don't always merge back into one another and back into the macOS Container. It is possible to merge those partitions back using the command line. I posted some instructions in another post here (may need to be modified a bit for your case since I wrote those for two specific cases, but there should be enough information there to figure it out if modifications are needed for your case), otherwise it may be easier to just start over with a clean install of macOS on the whole physical SSD (Doesn't hurt to experiment here since you have no data on either partition):

Merge (free space) item back into APFS Container -- HWTech - Apple Community

Merging multiple partitions back into APFS Container -- HWTech - Apple Community

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Answer 2

RoboMcd Author

Level 1

24 points

Mar 17, 2025 2:21 PM in response to HWTech

Deleted bootcamp (no problem) and started again. Found out what went wrong: weird behavior by Appel and me not paying attention.

Below the image when I started again.

Seems ok, so I push install. Then seemingly the same window popped up again with a small difference. Suddenly the partition has been changed to 42 GB, exactly as last time.

This time I paid attention and saw this pop-up was different. So I put the partition back to 250-750 and pushed install again. This time all went OK, without problem. Startup time now for Mac and for Windows is around 15 seconds!

Only problem now: MS did not find a digital license of my previous W10 installation on this laptop and keeps asking for a product key, not offering any other option. Now our non-profit has several licenses for Windows Pro, but MS does not recognize them anymore as valid and unfortunately the Volume License Service has been replaced with something else which is giving me problems. I am getting soooo tired from this.

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Answer 3

g_wolfman

Level 4

2,908 points

Mar 17, 2025 3:22 PM in response to RoboMcd

Did you deactivate Windows in your previous installation before wiping it? I suspect MS still thinks it is in use. You should be able to log into your account on microsoft.com and check your installations there - and removing the activation belonging to your previous installation should free the license for reassignment.

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Answer 4

g_wolfman

Level 4

2,908 points

Mar 15, 2025 9:39 AM in response to RoboMcd

You sure that Apple isn't reporting the drive sizes in Base10 and Windows in Base2? 1 TB = 931 TiB, so the numbers look about right to me - no missing space at all.

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