Bootcamp Partition not working after Yosemite Upgrade

The large gap between GPT3 and GPT4 indicates the usual Yosemite malady.

Please download Testdisk and GPT Fdisk and start a Testdisk scan.

http://www.cgsecurity.org/wiki/TestDisk_Step_By_Step

http://sourceforge.net/projects/gptfdisk/

Please see Lost my Windows 7 Boot Camp partition after upgrading to Yosemite. Help! as a reference.

Testdisk initial UI screens can be seen here - https://imgur.com/a/PjmnK.

Please select /dev/rdisk0. It will give you a message about it being read only, which is not an issue, since we are just reading, but not modifying anything via Testdisk.

In most cases, the Quick Search does show a very likely candidate. The Deeper Search can take several hours (or overnight) to run.

We are interested in partitions which are MS Data and when the 'P' (List Files) command is used, it should look similar to the following.

This listing also shows a partition history of sorts, which shows the movement of partition headers.

Your GPT has

978325720 388589352

the gap between GPT3 and GPT4 starting at the first sector number here. You need to find a MS Data entry which is close to and just after this number. Please scroll down, there should be another page after you scroll past the last entry.

Please enter 'P' to list files and post a screen shot.

Here is the verification table that I built using your values.

Leave your Testdisk display and start a new Terminal Window. You need to use the following steps.

If you see any error messages during the following steps, please stop and post back here with the error message. The following steps have values from your Testdisk output (and you can verify) in Steps 7 and 8. Please notice the '+' sign in Step 8.

Rebuild GPT4 using start/end offsets

1. Sudo gdisk /dev/rdisk0
2. P (print the full list of parts)
3. D (delete)
4. 4 (part 4)
5. N (new part)
6. 4 (part 4)
7. 978327552 - Start offset in bytes (start point for Bootcamp part)
8. +486819833 - Size offset (as opposed to End offset)
9. 0700 (Windows part type)
10. P (print list of all parts just to see what changes will be made)
11. W (Write the new GPT)
12. Y (Yes! really write the new GPT)

This will delete and re-write the GPT partition info for /dev/disk0s4.

Rebuild MBR to match the new GPT information thus resetting the Hybrid MBR. Use defaults for other questions (like partition codes). The only values that need modifications are the Boot flags and step 10. Accept all other defaults that Gdisk offers. Please see the sample Q&A after these steps. Do not enter any text which is in parentheses.

1. Sudo gdisk /dev/disk0
2. P (Print list of parts)
3. R (Recover)
4. O (print current Hybrid MBR)
5. H (chooses Hybrid)
6. Partitions numbers to be hybridized: 2 3 4
7. Y (Good for GRUB question)
8. N (part 2 boot flag)
9. N (part 3 boot flag)
10. Y (part 4 boot flag make NTFS bootable partition)
11. O (print current Hybrid MBR)
12. W (Write the new MBR)
13. Y (Yes! write the new MBR)
14. Reboot

Here is sample Q&A for this section. Please notice the Press Enter/Return.

Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): Y

Creating entry for GPT partition #2 (MBR partition #2)

Enter an MBR hex code (default AF): Press Enter/Return

Set the bootable flag? (Y/N): N

Creating entry for GPT partition #3 (MBR partition #3)

Enter an MBR hex code (default AB): Press Enter/Return

Set the bootable flag? (Y/N): N

Creating entry for GPT partition #4 (MBR partition #4)

Enter an MBR hex code (default 07): Press Enter/Return

Set the bootable flag? (Y/N): Y

Test 1 - Does Bootcamp Volume show up in Finder?

Test 2 - Can you see files in Bootcamp Volume?

Test 3 - Can you select Bootcamp in System Preferences -> Startup Disk?

Test 4 - If Test 3 is successful, select Bootcamp and Click Restart.