I have a 2012 retina macbook pro 15 with bootcamp (and some other weird partitions I won't get into) and a hybrid MBR. Hybrid MBR is a technology used to boot Windows on a Mac - Bootcamp enables it.
After rebooting, the Yosemite installer said I couldn't install because it might break Bootcamp installs. Here's the fix:
1. Boot again
2. Go to Utilities > Disk Utility
3. Click Bootcamp or whatever partition you have Windows on
4. Reboot and try installing again, or else try without rebooting if you can
If you have any issues after installing Yosemite (which I did not), you should try two things:
1. Download gptfdisk
2. Open the Terminal and type $ sudo gdisk /dev/disk0
3. If the text "Found valid GPT with hybrid MBR; using GPT." is displayed near the bottom, move to step 12
4. Press r and press enter. Press p and press enter - this lists your partition table.
5. Press h and press enter. This creates a new hybrid MBR.
6. Type the numbers of partitions you want in the MBR. This means your Mac and Bootcamp partition numbers - usually 2 and 3, but it may vary with custom installations.
7. Follow the instructions, using default values where possible and only setting the bootable flag for the Windows installation.
8. Press o and enter. This will print the MBR table - verify that it seems right.
9. Press p and enter - same as last step but for the GPT table.
10. Press w and enter to write the tables to the disk and exit.
11. Try booting Windows
12. Make another Bootcamp install disk using Bootcamp assistant
13. Boot from it and click "Repair your computer" after selecting a language, keyboard, etc. Select your Boot camp installation - this step varies depending on the version of Windows you have.
14. Enter the command prompt and type the following three commands, pressing enter after each one and waiting for it to complete:
Bootrec.exe /FixMbr
Bootrec.exe /FixBoot
Bootrec.exe /RebuildBcd
15. Reboot your computer. If you encounter any issues, email me at llamaswill@gmail.com - I'm not responsible for any problems you may have etc. etc.
After rebooting, the Yosemite installer said I couldn't install because it might break Bootcamp installs. Here's the fix:
1. Boot again
2. Go to Utilities > Disk Utility
3. Click Bootcamp or whatever partition you have Windows on
4. Reboot and try installing again, or else try without rebooting if you can
If you have any issues after installing Yosemite (which I did not), you should try two things:
1. Download gptfdisk
2. Open the Terminal and type $ sudo gdisk /dev/disk0
3. If the text "Found valid GPT with hybrid MBR; using GPT." is displayed near the bottom, move to step 12
4. Press r and press enter. Press p and press enter - this lists your partition table.
5. Press h and press enter. This creates a new hybrid MBR.
6. Type the numbers of partitions you want in the MBR. This means your Mac and Bootcamp partition numbers - usually 2 and 3, but it may vary with custom installations.
7. Follow the instructions, using default values where possible and only setting the bootable flag for the Windows installation.
8. Press o and enter. This will print the MBR table - verify that it seems right.
9. Press p and enter - same as last step but for the GPT table.
10. Press w and enter to write the tables to the disk and exit.
11. Try booting Windows
12. Make another Bootcamp install disk using Bootcamp assistant
13. Boot from it and click "Repair your computer" after selecting a language, keyboard, etc. Select your Boot camp installation - this step varies depending on the version of Windows you have.
14. Enter the command prompt and type the following three commands, pressing enter after each one and waiting for it to complete:
Bootrec.exe /FixMbr
Bootrec.exe /FixBoot
Bootrec.exe /RebuildBcd
15. Reboot your computer. If you encounter any issues, email me at llamaswill@gmail.com - I'm not responsible for any problems you may have etc. etc.