Q: OS X doesnt boot, however it only boots to windows

Can you post the output of the following Terminal commands from OSX side?

diskutil list

diskutil cs list

sudo gpt -vv -r show /dev/disk0

sudo fdisk /dev/disk0

The "sudo" commands will prompt for your password, and it will not be echoed back. You may also see a warning about improper use of "sudo" and potential data loss due to "abuse" of the command.

Hi Loner T,

I have the same exact problem, and this is in fact the second time this has happened to me after a clean install of Windows 10 on a 2013 Mac Pro. Note the following:

• I used Disk Utility to create the Boot Camp partition. The option to install Windows in Boot Camp Assistant was greyed out.
• I used 'gdisk' to convert the MBR from hybrid to protective to bypass the MBR/GPT error in the Windows installer when trying to format the Boot Camp partition to NTFS, as detailed here.

I had no problems rebooting between OS X and Windows shortly after the install, but I believe it's after I had shutdown from OS X, I wasn't able to boot back in. I'm not sure if a shutdown in general caused this issue to arise, but I was last in Yosemite when I had turned off the Mac. Thankfully, I can boot into the OS X recovery partition and manage things there, which is where I restored the Mac partition from a Time Machine backup the first time this happened.

I was able to input the Terminal commands you suggested to Naveedw from there. My SDD doesn't use CoreStorage (No CoreStorage logical volume groups found), so I got no significant output there. Here's what I got otherwise:

Also, when holding down Option after the startup chime, I no longer see "Macintosh HD" as a drive option to boot into. However, in Windows, it appears alongside the C: drive and is even browse-able, but not a startup option in the Boot Camp Control Panel.

Extra information:

I found an old thread from 2010 – Restoring "Macintosh HD" GUID – where the user couldn't boot into OS X, perhaps under different circumstances. The solution there involved DISKPART and 'gdisk' for Windows, both of which I looked into. The first part involved using DISKPART to confirm the type/ID of the Mac partition. The second part is using 'gdisk' to change the Mac partition's GUID back to the proper code as noted in this support article: Changing letter designation of Mac OS X partition via Windows can lead to data loss.

Where I'm confused is that DISKPART shows the Mac partition type as ebd0a0a2-b9e5-4433-87c0-68b6b72699c7, which is not correct (I assume), but 'gdisk' shows the proper GUID code 48465300-0000-11AA-AA11-00306543ECAC (Apple HFS/HFS+). I hope this extra information helps, and thank you for your time.

Can you all this information on a new discussion? Your problem/issue is different from the OP.

EFI partition being corrupted is not a good thing, especially if it happens more than once.

I've created a new topic here: OS X won't boot after installing Windows 10 - Late 2013 Mac Pro. I figured I'd post here since duplicate threads are usually frowned upon.