Failed to booting Windows 10 with bootcamp

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Failed to booting Windows 10 with bootcamp

Hi guys,

I have been using iMac and bootcamp for Windows 10 successfully. In recent years, I only use windows and never use the macOS side.

Recently, I decided to use both Win and Mac for some reasons, and updated my MacOS to the latest version (Catalina, 10.15.6).

The problem appears after updating the macOS successfully when I tried to reboot with windows by selecting "BOOTCAMP Windows" in Startup disk panel in system preferences.

It just failed and the black screen showed up saying "No bootable device --insert boot disk and press any key".

After seeing that, I turned off Mac and restart it using power button, while pressing Option(Alt) key to select startup disk option using startup manager (in booting time). Strangely, however, only the "Macintosh HD" disk option appears and the "Bootcamp Windows 10" disk option does not show up.

Therefore, at this time, i have no way to go back to the Windows 10 (By the way, the files and directories in Bootcamp partition can be found and accessed with Finder app which at least shows that the partition and Windows are not completely destroyed).

I am not sure whether the update of MacOS is the reason of the problem.

Can anyone give some advice to solve this problem and successfully boot with windows?

Many thanks in advance.

iMac Line (2012 and Later)

Posted on Sep 3, 2020 9:51 PM

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Answer 1

Top-ranking reply

Loner T

Level 9

59,513 points

Sep 6, 2020 10:02 AM in response to ylee198

The default installation mode on a late 2013 Mac is legacy BIOS. macOS Catalina can delete the MBR. Are you able to see Windows files in macOS Finder? If yes, the issue can be corrected fairly easily.

Also, from macOS Terminal, post the output of

sudo gpt -vv -r show /dev/disk0

sudo fdisk /dev/disk0

You may need to temporarily disable SIP in Local Recovery using csrutil.

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Answer 2

ylee198 Author

Level 1

8 points

Sep 6, 2020 5:08 PM in response to Loner T

Thanks for the detailed explanation.

I can see the Window files in macOS Finder.

Following lines are the output of the command: sudo gpt -vv -r show /dev/disk0

------------------------------------------------------------------------------------------------

gpt show: /dev/disk0: mediasize=121332826112; sectorsize=512; blocks=236978176

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 236978175

start size index contents

0 1 PMBR

1 1 Pri GPT header

2 32 Pri GPT table

34 6

40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B

409640 236568496 2 GPT part - 7C3457EF-0000-11AA-AA11-00306543ECAC

236978136 7

236978143 32 Sec GPT table

236978175 1 Sec GPT header

------------------------------------------------------------

Also, the following is the output of the command: sudo fdisk /dev/disk0

------------------------------------------------------------

Disk: /dev/disk0 geometry: 14751/255/63 [236978176 sectors]

Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: EE 1023 254 63 - 1023 254 63 [ 1 - 236978175] <Unknown ID>

2: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

3: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

------------------------------------------------------------------------------------------------

thanks.

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Answer 3

ylee198 Author

Level 1

8 points

Sep 6, 2020 7:11 PM in response to Loner T

You are right. It seems that disk1 is for Bootcamp and disk2 is for Macintosh.

Output of the comments for the disk1 is as follows:

>> sudo gpt -vv -r show /dev/disk1

gpt show: /dev/disk1: mediasize=1000204886016; sectorsize=512; blocks=1953525168

gpt show: /dev/disk1: Suspicious MBR at sector 0

gpt show: /dev/disk1: Pri GPT at sector 1

gpt show: /dev/disk1: Sec GPT at sector 1953525167

start size index contents

0 1 MBR

1 1 Pri GPT header

2 32 Pri GPT table

34 6

40 409600 1 GPT part - C12A7328-F81F-11D2-BA4B-00A0C93EC93B

409640 777334744 2 GPT part - 7C3457EF-0000-11AA-AA11-00306543ECAC

777744384 1175779328 3 GPT part - EBD0A0A2-B9E5-4433-87C0-68B6B72699C7

1953523712 1423

1953525135 32 Sec GPT table

1953525167 1 Sec GPT header

----------------------------------------------------------------------------------------------

>> sudo fdisk /dev/disk1

Disk: /dev/disk1 geometry: 121601/255/63 [1953525168 sectors]

Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: EE 1023 254 63 - 1023 254 63 [ 1 - 409639] <Unknown ID>

2: FF 1023 254 63 - 1023 254 63 [ 409640 - 777334744] Xenix BBT

3: 0C 1023 254 63 - 1023 254 63 [ 777744384 - 1175779328] Win95 FAT32L

4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

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Answer 4

ylee198 Author

Level 1

8 points

Sep 7, 2020 7:14 AM in response to Loner T

Thanks again for your kindness!

Output of the commands you said is as follows:

sudo fdisk -e /dev/disk1

fdisk: could not open MBR file /usr/standalone/i386/boot0: No such file or directory

Enter 'help' for information

fdisk: 1> p

Disk: /dev/disk1 geometry: 121601/255/63 [1953525168 sectors]

Offset: 0 Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: EE 1023 254 63 - 1023 254 63 [ 1 - 409639] <Unknown ID>

2: FF 1023 254 63 - 1023 254 63 [ 409640 - 777334744] Xenix BBT

3: 0C 1023 254 63 - 1023 254 63 [ 777744384 - 1175779328] Win95 FAT32L

4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

fdisk: 1> setpid 3

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

3: 0C 1023 254 63 - 1023 254 63 [ 777744384 - 1175779328] Win95 FAT32L

Partition id ('0' to disable) [0 - FF]: [C] (? for help) 07

fdisk:*1> flag 3

Partition 3 marked active.

fdisk:*1> p

Disk: /dev/disk1 geometry: 121601/255/63 [1953525168 sectors]

Offset: 0 Signature: 0xAA55

Starting Ending

#: id cyl hd sec - cyl hd sec [ start - size]

------------------------------------------------------------------------

1: EE 1023 254 63 - 1023 254 63 [ 1 - 409639] <Unknown ID>

2: FF 1023 254 63 - 1023 254 63 [ 409640 - 777334744] Xenix BBT

*3: 07 1023 254 63 - 1023 254 63 [ 777744384 - 1175779328] HPFS/QNX/AUX

4: 00 0 0 0 - 0 0 0 [ 0 - 0] unused

fdisk:*1>

Thanks.

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Answer 5

Loner T

Level 9

59,513 points

Sep 4, 2020 6:22 AM in response to ylee198

What is the year/model of your Mac (do not post the serial number)? macOS upgrades are known to have issues with legacy BIOS installations.

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Answer 6

Sep 3, 2020 10:05 PM in response to ylee198

Catalina is the worst macOS so I can imagine Catalina is the problem I strongly recommend backing up ALL your stuff and rolling back to Mojave

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Answer 7

ylee198 Author

Level 1

8 points

Sep 4, 2020 1:18 AM in response to The_Hackintosh

Thanks for the reply. I will consider downgrading of the OS if the problem is not solved with Catalina

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Answer 8

ylee198 Author

Level 1

8 points

Sep 5, 2020 12:55 AM in response to Loner T

I am using 21.5-inch, Late 2013 iMAC. Do you also recommend to downgrade the macOS?

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Answer 9

Loner T

Level 9

59,513 points

Sep 6, 2020 6:50 PM in response to ylee198

You seem to have a Fusion drive. Can you post the output of the same commands for disk1?

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Answer 10

Loner T

Level 9

59,513 points

Sep 7, 2020 7:02 AM in response to ylee198

Run

sudo fdisk -e /dev/disk1

p

setpid 3

07

flag 3

p

and post the output, before we write the modified MBR to disk.

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Answer 11

Loner T

Level 9

59,513 points

Sep 7, 2020 9:24 AM in response to ylee198

Type 'w' to write the MBR. You may also need to run Windows Repair, if Windows still does not boot.

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Answer 12

ylee198 Author

Level 1

8 points

Sep 7, 2020 8:15 PM in response to Loner T

Thank you Loner T!

Finally, booting is done successfully. It would never have been successful without your kind advice.

Thank you again. Hope you have a great day

Best regards, ylee.

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Answer 13

Loner T

Level 9

59,513 points

Sep 7, 2020 9:18 PM in response to ylee198

Excellent!

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