If you're still having this issue, these steps should fix it.
Boot into Recovery Mode (cmd+R).
- Utilities menu > Terminal > Type:
csrutil disable
- Reboot normally
First, download gdisk (sourceforge.net/projects/gptfdisk/files/gptfdisk/1.0.0/gdisk-binaries/gdisk-1.0.0.pkg/download) and run the installer package.
Then run gdisk from a terminal window and run the v (verify command).
- sudo gdisk /dev/disk0
- Command (? for help): v
Given what you've said, it'll probably say:
Warning! Mismatched GPT and MBR partition! MBR partition 4, of type 0x07, has no corresponding GPT partition! You may continue, but this condition might cause data loss in the future!
Identified 1 problems!
Next, display the MBR partition table and make note of the start and end sectors for your BOOTCAMP partition.
- Command (? for help): r
- Recovery/transformation command (? for help): o
This should be partition 4 unless you've added additional partition(s), which is not officially supported by Boot Camp. It should show something like this:
Disk size is 1953525168 sectors (931.5 GiB)
MBR disk identifier: 0x7C170CB2
MBR partitions:
Number Boot Start Sector End Sector Status Code
1 1 409639 primary 0xEE
2 409640 975693095 primary 0xAF
3 975693096 976962631 primary 0xAB
4 * 976963584 1952806911 primary 0x07
Next, display the GPT partition table information:
- Recovery/transformation command (? for help): m
- Command (? for help): p
Number Start (sector) End (sector) Size Code Name
1 40 409639 200.0 MiB EF00 EFI System Partition
2 409640 975693095 465.1 GiB AF00 Customer
3 975693096 976962631 619.9 MiB AB00 Recovery HD
4 976963584 1953523711 465.7 GiB 0700 BOOTCAMP
Compare the start and end sectors for partition 4 to the MBR partition 4 start and end sectors. Most likely the start sectors will match, but the end sectors will be different.
Next, delete the GPT partition 4. (Note: this does not delete the actual partition from disk. It only deletes gdisk's in-memory representation of the GPT).
- Command (? for help): d
- Partition number (1-4): 4
Now, create a new partition 4 using the start and end sector values from the MBR partition 4:
- Command (? for help): n
- Partition number (4-128, default 4): 4
- First sector (34-1953525134, default = 976962632) or {+-}size{KMGTP}: 976963584
- Last sector (976963584-1953525134, default = 1953525134) or {+-}size{KMGTP}: 1952806911
- Current type is 'Apple HFS/HFS+'
- Hex code or GUID (L to show codes, Enter = AF00): 0700
- Changed type of partition to 'Microsoft basic data'
Now, change the name of the new partition 4 to BOOTCAMP:
- Command (? for help): c
- Partition number (1-4): 4
- Enter name: BOOTCAMP
Run the verify command. It should report no problems. If it still reports a problem, quit (q command) and start over.
Command (? for help): v
If everything checks out, write new partition table to disk and exit.
Command (? for help): w
Reboot and test your dual boot setup to verify all is working correctly.
Boot back into Recovery Mode (cmd+R).
- Utilities menu > Terminal > Type:
csrutil enable
- Reboot normally
-Max.
