Level 1

4 points

Bootcamp partition missing after update to Catalina

I have a MacBook Air (2015) with Bootcamp on it which I use to run Windows 10. MacOS updated to Catalina (10.15.4) and I now I can't boot into Windows. I've tried via the startup disk menu and by holding down the alt/option key during boot but the Windows option doesn't show up in either of these.

The Disk Utility didn't show the partition, but the Macintosh HD partition was 170GB (out of the 251GB SSD) which is correct as the windows partition was 80GB.

I've been reading through similar threads which Loner T has been answering such as this one: https://discussions.apple.com/thread/8369480?page=1 and tried to follow through the steps. My results were very similar to that thread so I ran the command in Internet Recovery mode:

diskutil unmount disk0

gpt add -i 3 -b xxxxxx -s yyyyyyyyyy -t windows /dev/disk0

diskutil repairDisk disk0

with my specifics in there. That made the partition show up in disk utility greyed out:

Downloaded testdisk and started through the teskdisk process. Got to

https://discussions.apple.com/thread/7275705?answerId=29089993022#29089993022

but when I pressed p on my MS Data entry it gave me an error message instead:

So bit out of my depth here. Anyone able to offer advice? Should I continue trying to get testdisk to work or is there another approach?

Here's the output of the commonly asked for commands:

common commands

Thanks in advance

MacBook Air 13", macOS 10.15

Posted on May 22, 2020 12:06 AM

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33 replies

gingerkiwi Author

Level 1

4 points

May 22, 2020 5:46 PM in response to Loner T

I got to this point (following this thread https://discussions.apple.com/thread/7275705) in the quick search. Then when I press p I get the error shown in the second pic about

gingerkiwi Author

Level 1

4 points

May 22, 2020 8:10 PM in response to Loner T

When I press p I hit the error in the photo above

gingerkiwi Author

Level 1

4 points

May 22, 2020 8:20 PM in response to Loner T

sudo dd if=/dev/rdisk0s3 count=5 2>/dev/null | hexdump -C

Password:

00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|

00000a00

gingerkiwi Author

Level 1

4 points

May 22, 2020 8:30 PM in response to Loner T

From the output of gpt -vv -r show -l /dev/disk0. I used the values for the blank partition which seemed the right size.

gingerkiwi Author

Level 1

4 points

May 23, 2020 4:27 PM in response to Loner T

Not in the output of the analyse disk quick search, is there another testdisk function I should run to check?

gingerkiwi Author

Level 1

4 points

May 24, 2020 2:19 AM in response to Loner T

Actually there were two MS Data entries in the step before Quick search as shown in this pic:

gingerkiwi Author

Level 1

4 points

May 25, 2020 2:38 PM in response to Loner T

See what you mean about it being very slow. Finally finished. Here's the ouput of 1. the deep search result 2. the screen after I hit continue, 3. the screen after I pressed p on the MS Data section:

gingerkiwi Author

Level 1

4 points

May 25, 2020 5:12 PM in response to Loner T

No, I tried to continue to see if there was one on the next screen for EFI, but it said nothing available then quit back to this screen:

gingerkiwi Author

Level 1

4 points

May 25, 2020 6:12 PM in response to Loner T

Whoops sorry. should have tried that! Yep that ran. No Microsoft directory there:

Loner T

Level 9

59,536 points

May 25, 2020 6:32 PM in response to gingerkiwi

Do you have a backup of your Windows non-OS files?

gingerkiwi Author

Level 1

4 points

May 25, 2020 6:43 PM in response to Loner T

Yep anything crucial is on Git or google drive

Loner T

Level 9

59,536 points

May 25, 2020 7:10 PM in response to gingerkiwi

You may want to use BC Assistant and Remove the partition, before you try to re-install Windows. Run a SMC and NVRAM Reset after Windows is removed.

gingerkiwi Author

Level 1

4 points

May 22, 2020 5:22 PM in response to Loner T

To check I understand correctly, output of $ sudo gpt -vv -r show -l /dev/disk0

Password:

gpt show: /dev/disk0: mediasize=251000193024; sectorsize=512; blocks=490234752

gpt show: /dev/disk0: PMBR at sector 0

gpt show: /dev/disk0: Pri GPT at sector 1

gpt show: /dev/disk0: Sec GPT at sector 490234751

start size index contents

0 1 PMBR

1 1 Pri GPT header

2 32 Pri GPT table

34 6

40 409600 1 GPT part - "EFI System Partition"

409640 332031960 2 GPT part - "Customer"

332441600 157793119 3 GPT part - ""

490234719 32 Sec GPT table

490234751 1 Sec GPT header

so the start and size of partition is

332441600 157793119

and the start and size from the testdisk quick search is

332441600 157792256

so the difference of 863 sectors is the headers? Or is there more stuff in there too?

gingerkiwi Author

Level 1

4 points

May 22, 2020 5:57 PM in response to gingerkiwi

Noticed that the first pic says NTFS found using backup sector. Should I follow through the instructions in the TestDisk documentation?

7.4 Repairing FAT32, exFAT and NTFS boot sector using TestDisk

The boot sector is a sector containing information required to access any files from a FAT, exFAT or NTFS filesystem.

FAT32 and NTFS filesystems have a main boot sector and a backup. If the main boot sector is damaged, the filesystem

is listed as raw or unreadable. TestDisk is able to use the backup boot sector to repair the main boot sector:

• start testdisk

• select the device containing the partition (avoid drive letter like D:)

• confirm the partition table type

• go in the Advanced menu

• select the partition

• choose Boot

If the boot sector is damaged, Boot sector: Bad will be shown. If the backup is OK, Backup boot sector: Ok will also

be listed.

• choose BackupBS

• confirm

• Quit

• restart the computer

Loner T

Level 9

59,536 points

May 23, 2020 8:01 AM in response to gingerkiwi

Does Testdisk show you any other MS Data partition entries? If the partition was discovered using a backup sector, we can try chkdsk, but without the header, a chkdsk does not help in rebuilding the MFT.

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Bootcamp partition missing after update to Catalina