Bootcamp partition map got messed up after recent Windows 10 update

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Level 1

23 points

Bootcamp partition map got messed up after recent Windows 10 update

After a recent Win10 update I can no longer boot into Windows, which is installed with Bootcamp Assistant. I use MBP15" (mid-2018). Now when I try to boot into Windows I get the following error

This is how my internal MacBook SSD disk looks like

Tried the First Aid route via MacOS Disk Utility (while in normal boot and while in Recovery boot) - this is what I get

Any way to repair partition map to be able to boot into Windows again? BTW, my Windows partition is still accessible in MacOS - I can see all the files there. I just cannot boot into Windows. Any suggestions/ideas/terminal commands would be much appreciated.

MacBook Pro 15”, macOS 10.14

Posted on Apr 16, 2019 12:48 PM

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Answer 1

rchomskis Author

Level 1

23 points

Apr 17, 2019 3:25 PM in response to rchomskis

Nevermind. I found that WinClone can fix the "bless tool" issue - and it fixed for me! I can now boot into BCP again! 🥳

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Answer 2

Loner T

Level 9

59,536 points

Apr 17, 2019 3:07 PM in response to rchomskis

You can convert the 134MB slice to free space, merge it back into the macOS side, which will give you the three partitions. We can then try to do a startup repair. If you can see Windows files in macOS finder, I strongly recommend copying all your important non-OS files to an external disk.

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Answer 3

Loner T

Level 9

59,536 points

Apr 17, 2019 4:30 AM in response to rchomskis

A 2018 Mac does not use a MBR. MBR is valid for 2014 or older Macs. It should be removed.

Is Windows a new installation. Can it be removed/re-installed?

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Answer 4

rchomskis Author

Level 1

23 points

Apr 16, 2019 10:27 PM in response to Loner T

Very good question. yesterday my Windows partition was disk0s3. but after googling I found some terminal commands for rebuilding standard MBR (see screenshot below).

Also, maybe the numbering changed after I tried to temporarily resize the Macintosh HD partition (hoping this action will trigger partition map rewrite)

So to answer your question - either by two of the above unsuccesful/wrongly done approaches (MBR rebuilding or partition resizing). ☺️

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Answer 5

rchomskis Author

Level 1

23 points

Apr 17, 2019 6:39 AM in response to Loner T

How do I remove disk0s3? Through Disk Utility in Recovery mode?

Windows installation is not a new one. I'm definetely not looking forward to reinstalling system/software 😱 This would be my last resort. Any way to rewrite/rebuild Windows partition boot map or something? I actually tried Windows rescue disk approach, but did not work either, so I am not sure if Windows reinstallation will not be a destructive process. I wouldn't really like to loose all my Windows files/software settings/licences... 🤔

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