disk0s2 can't mount - Partition shows as "MBR part 255"

Something happened with my BootCamp configuration and now my MBP will only boot into windows. When I booted into recovery and checked the Disk Utility, the "disk0s2" was unmounted and couldn't be mounted. I tried to follow guides where people had similar issues, however, I believe I've dug my hole deeper.

I'm getting an error that there's a "suspicious" and "malformed" MBR at sector 0. I'm also getting an error the there is "no space available on device" when trying to add the partition back.

The image below shows my current gpt output. Can anyone help get my OSX partition back to bootable?

Thank you in advance!!!

MacBook Pro

Posted on Jul 31, 2018 1:44 PM

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Loner T

Level 9

59,536 points

Posted on Aug 1, 2018 4:41 PM

Run

gpt remove -i 2 /dev/disk0

gpt add -i 2 -b 409640 -s 158339032 -t apfs /dev/disk0

If 'apfs' gives you an error, then

gpt add -i 2 -b 409640 -s 158339032 -t 7C3457EF-0000-11AA-AA11-00306543ECAC /dev/disk0

Now run

diskutil repairDisk disk0

and reboot and test if macOS will boot properly.

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81 replies

Loner T

Level 9

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Jul 31, 2018 2:34 PM in response to langridgedean

What is the year/model of your Mac (do not post the serial number) and the macOS version?

Jul 31, 2018 8:36 PM in response to Loner T

It's a 2013 MBP. If you need more info than that, let me know.

As for the macOS, I'm not sure of specific revision, but it's running High Sierra.

Loner T

Level 9

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Aug 1, 2018 3:46 AM in response to langridgedean

A 2013 MBP should have an SSD which would have been converted to APFS. Do you recall the file system on the macOS side?

Aug 1, 2018 8:53 AM in response to Loner T

Unfortunately, I don't. I can confirm it has an SSD. However, I'm not sure on the details of the file system.

Aug 2, 2018 11:50 AM in response to Loner T

Unfortunately, I do not. I ran the commands and restarted.

Aug 3, 2018 7:26 PM in response to langridgedean

Here's an image of the "fdisk" output:

Loner T

Level 9

59,536 points

Aug 3, 2018 9:25 PM in response to langridgedean

It matches the GPT3 entry. This is just to record the current state, before we rebuild the GPT and the MBR.

Aug 5, 2018 10:02 AM in response to Loner T

Do we have next steps for rebuilding the GPT and MBR?

Aug 6, 2018 7:25 AM in response to Loner T

When I reboot and hold Alt/Option, "Internet Recovery" is my only boot option. If I don't hold Alt/Option, it comes up to the flashing folder with the question mark.

Loner T

Level 9

59,536 points

Aug 6, 2018 7:30 AM in response to langridgedean

Do you have an external disk 32+GB on which we can install High Sierra temporarily?

Aug 6, 2018 8:52 AM in response to Loner T

I don't have one with me, but I can get one. Will I need another Mac to install High Sierra on the external disk, or can I use Windows? Can you provide instructions on how to do that?

Aug 6, 2018 6:33 PM in response to Loner T

High Sierra is currently installing to an external hard drive. I will be able to continue with the next steps when it completes.

Loner T

Level 9

59,536 points

Aug 7, 2018 1:25 AM in response to langridgedean

Post back when you are ready.

Aug 7, 2018 5:09 AM in response to Loner T

I am ready. Currently booted into High Sierra on the external hard drive. It is High Sierra 10.13.6.

Aug 9, 2018 6:14 AM in response to Loner T

I do not have a full back up, but we can proceed. I hope to preserve as much as possible, but I know right now that nothing is accessible.

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disk0s2 can't mount - Partition shows as "MBR part 255"