I am using a 2010 27" iMac with Mac OS High Sierra and Windows 10 via Bootcamp. Recently, I have had an issue where every Mac update renders the Windows partition unbootable. This means that after every Mac OS update, I need to use Gdisk to fix the hybrid partition table so I can boot Windows again. Unfortunately, this time after I did the repair the Mac partition will no longer boot. Is there a way of fixing the hybrid partition table from Windows so I can get the Mac Partition to boot again, it doesn't show up in the ALT menu on startup and if I try to boot using Refind, the boot process begins but doesn't complete with a crossed out circle on the screen.
When I open Fdisk and run list partition, I get the following:
DISKPART> LIST PARTITION Partition ### Type Size Offset ------------- ---------------- ------- ------- Partition 1 Primary 1370 GB 512 B Partition 2 Primary 14 GB 1370 GB Partition 3 Primary 478 GB 1384 GB Partition 4 Primary 16 KB 1863 GB
The Mac OS is installed on Partition 1, Partition 3 is the Boot Camp one. The Mac OS partition still doesn't show up, even if I try to reinstall High Sierra from a USB drive.
What is the procedure to try and restore the Mac Partition? I think I will need to use GDisk from the Boot Camp partition. I think I messed up the last time I used GDisk on the Mac to get Windows working again so I want to be careful this time! Windows is working so how can anyone help me use FDisk/GDisk on Windows to restore the partition table to a working state?