"Missing Operating system_ " After installing Yosemite

Ok, ready for the partition manipulation command Loner .

😐 Thanks for the help.

I had not seen updates from this thread.abughareeb (Sorry).

You want to use Gdisk and set the MBR hex code to AF (not AF05), and then try diskutil cs convert. The syntax is indicated below, but you need to pick the correct slice. You do not need the passphrase part, but just the DeviceNode part, which in your case is disk0s2.

diskutil cs convert

Usage: diskutil coreStorage convert

MountPoint|DiskIdentifier|DeviceNode

[-stdinpassphrase | -passphrase [passphrase]]

Convert a regular JHFS+ partition into a CoreStorage logical volume.

The file system must be mounted and resizable (i.e. Journaled HFS+).

Ownership of the affected disk is required.

Loner T- You seem to be the Go To Man on this problem. I've followed these threads to try to solve my problem, but either they seem to dead end, or the posters you are helping disappear and I don't the final solution. So I'm going to reach out with mine. Hopefully you can help.

I had a MacBookPro that I was using that we set up a Bootcamp partition on, and installed Windows 8.1. On the partition I installed several thousands of dollars worth of VFX software (Maya, 3ds Max, etc) and everything ran fine. I recently got a new MacBookPro myself and wanted to move everything over. I used the same method to set up the partition, and then used a program called Winclone to make disc image of Bootcamp, and migrated it over to my new computer. Once it was done, I booted up Windows just fine and started up all of the programs and they ran. Yay!! I didn't try to reboot for about a week and when I did, I got the same black screen issue that everyone is talking about. Well, my bad during that week away from Windows, I followed a prompt and upgraded to Yosemite. I tried Apple, Windows, and Winclone support to no avail. I even went to the Genius Bar and they ran a bunch of diagnostics, couldn't find anything, but while I was there we tried to boot Windows, it worked and the programs ran again. But the time I got home and tried again, back to black.

So I have followed your instructions for other as close as I can, and have run the deep scan with testdisk and found the MS Data with my programs. And that's where I'm stuck. I downloaded gdisk, but once I open the package, I don't where it installs. This is where it gets over my head, it's probably in dos somewhere, huh?

Anyway, please help. I can't afford to scrap the partition and try to start again to get all those programs relicensed. Let me know what you need to see to get me started, and how to use gdisk.

Thanks in advance, you are amazing.

Can you start a new thread, post the output of Testdisk and the usual commands? If you need exact commands, let me know.

Loner T,

Thanks so much. I work in 3d graphics (self-taught) but am completely clueless on digging into the OS or working in DOS or command prompt. So yes, if possible I will need you to walk me through the steps. No one else seems to know where the problem lies. I'm also not familiar with Terminal. So I'm not even sure how to copy the screen to post for you. (I know, right? I can create 3d animation, but I can't do this.

In Applications -> Utilities -> Terminal type the following command (or triple click on the line and use Command+C (Copy) and Paste (Command+V) in the Terminal window).

which gdisk

On my machine the output is as follows (I have added a Unix 'ls' - List Directory command to make it easier).

which gdisk

/usr/sbin/gdisk

ls -l /usr/sbin/gdisk

-rwxr-xr-x 1 MyName staff 212124 Feb 17 2014 /usr/sbin/gdisk

Okay, I started a new thread (title is "Need help! Windows won't boot in partition.")

Let me know if what I posted is what you needed. I copied what TestDisk what showing. I didn't want to open Terminal in case it would close what I've already analyzed in TestDisk.

Hey Loner T, You seem to be the Top man helping everyone, and i noticed you were asking people to open new discussions so is easier to keep track of the problems, i have open a new one here Lost Windows partition after upgrading to Yosemite any help would be much appreciated

I too have been having this problem, so I have tried to follow the above steps, but do not know what to look for, or what to do since I do not understand. Could you please help me?

I haven't done anything else, as I don't want to mess anything up, and don't know what else to do. Sorry for the big pictures, I'm not sure how that happened. Also, here are the problems I've had, and what I tried to resolve such.

First, I had a problem as I tried to resize a partition from the Disk Utility, thus causing the problem that I couldn't access my Windows partition from the Startup Disk in System Preferences or by booting up and pressing the option key, as it has completely disappeared from both. I used the instructions from this website: http://nerdr.com/bootcamp-partition-lost-repairing-mac-partitions/. This caused the Windows partition to come back up by pressing the option key while the computer was starting up, but not on the Startup Disk in System Preferences. When I tried to boot using Windows partition, it just gave me a black screen with missing operating system in the top left. I tried to use my Windows Installation USB, but I ran into the problem of having no mouse or keyboard while trying to use it. I couldn't solve this, so I came here instead.

Here is the response from sudo gpt -vv -r show /dev/disk0

Here is how deep I've gotten.

Partitions

Listing the files of the first MS data gives this.

The second MS data, however, gives this.

The third one seems to be almost the same as the first one.

Install GPT Fdisk (aka gdisk). 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 (this is called offset notation). The text in parentheses is for informational purpose to describe theaction being taken. Gdisk has one-character commands except when entering numbers.

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. 314179584 ( - Start offset in sectors or the start point for Bootcamp part)
8. +176054264 ( - 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 thesample Q&A as an example. These steps can be repeated if you make a mistake before you get to Step 12, otherwise start from Step 1 for these steps. Step 6 has numbers which are typed with a space between the numbers.

1. Sudo gdisk /dev/rdisk0
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.

I can boot up to it, but it still has a problem. It says something along the lines of the startup has failed, maybe due to a software change. My USB works, but trying to repair it doesn't work, as it says that the USB doesn't have the files. I will try to re-download format and create a new USB from Bootcamp later.

Your original BCA-created USB also has repair capability. If you get only an Install option, create a new USB installer. If you Mac has a built-in Optical drive, you need to use a physical Windows DVD to repair.

I reinstalled the stuff on the USB, and when I chose the repair option, it gave me a box saying that it found problems, and after I clicked repair, it just said Failed to save startup options. Booting into windows, it gave an error saying error occurred while attempting to read the boot configuration data. What do I do now?

Please see https://support.microsoft.com/en-us/kb/927392 and how to rebuild your BCD.