Bootcamp Partition Missing When Booting

iMac (21.5-inch, Late 2012) and Windows 10.

A bit of background, I didn't resize the Bootcamp partition as MrShady5721 did, I shrunk the Mac partition by 32GB so that I could then increase the Windows partition into that unallocated space. After I had shrunk the Mac partition, the Windows partition was unavailable when holding 'Alt' on boot.

From Applications -> Utilities -> Terminal, please post the output of the following commands...

diskutil list

diskutil cs list

Text output is preferred.

/dev/disk0 (internal, physical):

#: TYPE NAME SIZE IDENTIFIER

0: GUID_partition_scheme *1.0 TB disk0

1: EFI EFI 209.7 MB disk0s1

2: Apple_CoreStorage mi SSHD Boot 936.4 GB disk0s2

3: Apple_Boot Recovery HD 650.0 MB disk0s3

4: Apple_HFS Untitled 30.8 GB disk0s4

5: Microsoft Basic Data BOOTCAMP 32.0 GB disk0s5

/dev/disk1 (internal, virtual):

#: TYPE NAME SIZE IDENTIFIER

0: mi SSHD +936.0 GB disk1

Logical Volume on disk0s2

55E6F5AA-3EB2-4FCD-BB26-59FCAF9B0485

Unlocked Encrypted

CoreStorage logical volume groups (1 found)

|

+-- Logical Volume Group CA02B458-F64D-4C3C-9846-8F33F9C28C2F

=========================================================

Name: mi SSHD Boot

Status: Online

Size: 936371281920 B (936.4 GB)

Free Space: 18960384 B (19.0 MB)

|

+-< Physical Volume A17A1C8C-CA44-4352-B096-1ABD98D971DA

| ----------------------------------------------------

| Index: 0

| Disk: disk0s2

| Status: Online

| Size: 936371281920 B (936.4 GB)

|

+-> Logical Volume Family E8D922B5-0609-43E2-99C6-5CBF49334FAF

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

Encryption Type: AES-XTS

Encryption Status: Unlocked

Conversion Status: Complete

High Level Queries: Fully Secure

| Passphrase Required

| Accepts New Users

| Has Visible Users

| Has Volume Key

|

+-> Logical Volume 55E6F5AA-3EB2-4FCD-BB26-59FCAF9B0485

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

Disk: disk1

Status: Online

Size (Total): 936000000000 B (936.0 GB)

Revertible: Yes (unlock and decryption required)

LV Name: mi SSHD

Volume Name: mi SSHD

Content Hint: Apple_HFS

Please post the output of

sudo fdisk /dev/disk0

If you notice, the 30.8GB partition has become disk0s4 pushing Windows to disk0s5. This can cause booting issues. Is W10 and upgrade from W7/W8.1 or a clean installation?

Disk: /dev/disk0 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 - 1953525167] <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: 07 0 0 0 - 0 0 0 [ 0 - 0] HPFS/QNX/AUX

Clean (purchase and) installation of W10

Can you use Re: [Help] Can't boot to windows (8.1) after resizing partition and rebuild your MBR and test? This may not work, if your W10 installation is UEFI. Does the Audio work correctly on W10 on your iMac?

Thank you. I will try that at the next available opportunity.

Not sure if W10 is UEFI, it was installed via Bootcamp IIRC. The audio worked fine in W10

mac-interactive wrote:

Not sure if W10 is UEFI, it was installed via Bootcamp IIRC. The audio worked fine in W10

It seems to be legacy BIOS. Can't resize Macintosh HD partition is not a definitive test, but you can check.

Thanks again for your help. I've left it so long I've decided to just wipe the partition and reinstall Windows 10 etc.

Please post back if you run into any issues with the W10 installation.

No issues at all thanks. I now have my bootcamp partition twice as large as it was so there should be enough room for Windows Updates. Thanks again for your help and Happy New Year to you.

Please remember to back up your files on a regular (preferably daily basis).

Thanks, it works for me.