El Cap seems to have nuked my Bootcamp created Windows 10 partition and it won't let me install one outright. I get the 'This is GPT partition style' error, and I'm not sure how to fix it under El Capitan. El Capitan 10.11.1, Fusion 7.1.3, Windows 10 BOOTCAMP no longer recognizes external USB HD. With Yosemite, Fusion 7.1.2, and Windows 10, all Fusion support for external USB HD worked. Fusion would prompt for connect to Mac or Windows, or could configure a given USB HD to always connect to Windows 10. Use this configuration extensively for backups. I have a brand new MacBook Pro with 16GB RAM running El Capitan - 10.11.4. I am, however having lots of problems with creating and installing Windows 10 using Boot Camp. I have had this working with Windows 10 once but made some fundamental errors. I resized the windows partition using a windows product so that I could add another partition. Hi, I have been asked to duel boot a friends iMac (27' Mid 2011) with Windows 10 using Bootcamp. He is running Bootcamp 6.0.1 which does support the installing of Windows 10, but according to the official Apple website, his mid 2011 iMac isn't listed as supporting Windows 10.

After entering the password it vanishes and only the Windows option is left. Trying to reinstall OSx: Since macOS Sierra is a later version than the Recovery Mode's El Capitan, it won't progress. To be able to write this post, I've plugged in my Windows 10 install USB, formatted the Windows partition and reinstalled Windows 10. This has worked.

I recently decided to run Kali Linux on my MacBook. I originally thought I'd just build it into a Virtual Machine (using Parallels), but was concerned that I might not have the control over the hardware that I'd need in order to make Kali effective as a learning environment. So, I set about working on a dual-boot scenario. Needless to say, I failed miserably when I opted to have Kali install Grub and it overwrote my primary Boot Manager on the Mac and rendered the system unbootable (and eventually unrecoverable). Thank goodness for good backups...

WARNING: Do not proceed with any of these steps unless you have the ability to restore a bare-metal backup. Everything I'm doing has the potential to trash all of the data on your computer, requiring a clean installation of macOS and subsequent data recovery from backups. I use a combination of Time Machine, CrashPlan, and Arq to back up my system, you should too.

Triple Boot the Right Way

If you're interested in triple booting your MacBook Pro, and Windows is going to be one of the Operating Systems you're going to boot, then take my word for it, this is the only way you want to accomplish this feat.

At a high level, the process goes like this:

1. Install Apple's Bootcamp and use it to install Windows 10
2. Use Windows 10 to shrink the Bootcamp partition, freeing up space to install Linux
3. Install Linux (I used Kali) into the newly freed space
4. Install rEFInd as a Boot Manager for all 3 OSes

To be fair, a lot of my instructions and the guide I initially followed, can be found here. However, several of the steps in that guide I didn't have to use at all, so I'm documenting my process here.

Install Apple's Boot Camp

Apple provides a supported method of installing Windows as a dual-boot option for Macintosh owners. There are several advantages to using Apple's process:

1. Apple supports this as a way to boot Windows
2. Apple provides native drivers for the hardware under Windows
3. You will have supported ways to control the Windows and macOS boot process on your MacBook from within Windows (via the Boot Camp Control Panel)

Apple's official documentation for Boot Camp is found here.

Follow Apple's instructions for installing Windows, but make sure you create the Windows partition approximately 64GB larger than what you want to end up with for Windows, that space will end up being given to Linux. Adjust if you wish, I used a 196GB partition for Windows 10, then split it into 128GB for Windows and 64GB for Linux (FYI, a Windows 10 installation with Office 365 installed takes up 68GB, so give yourself enough room under Windows).

Note: Apple only supports Windows 8.1, or newer, for hardware released after 2014. There is no way to install an earlier version of Windows using Boot Camp on newer hardware. See this table to check your hardware and what versions of Windows are supported on it.

Now that you have an Apple-supported dual-boot system running macOS and Windows 10 (presumably), it's time to perform the Linux installation.

Create Partition for Linux

For the purposes of this article, I'm going to install Kali Linux, that's what I used, but installation with ANY version of Linux should work the same way.

The first step is to shrink the Windows partition to make some space for Linux:

1. Boot into Windows 10
2. Right-click on the Start Menu and select Disk Management
3. Select the BOOTCAMP partition, right-click and select Shrink Volume
4. Enter the size, in megabytes, by which to shrink the volume. I shrunk mine by 64GB, so I entered 65,536

This image is AFTER I did my initial shrink and subsequent installation of Kali linux, you'll have fewer partitions when you do this. I also have an SD card mounted.

The shrinking process took a LONG time (~30 minutes), don't worry about it, let it run to completion and do not interrupt.

After the Volume shrinking process is completed, it's time to download some files to perform the installation; however, you probably want to do this under macOS, so first boot back to your macOS volume and the download them both:

1. Kali Linux, 64-bit, can be downloaded here
2. rEFInd, can be downloaded here

Place all of the rEFInd files (after unzipping) on a removable volume (SD Card, USB drive, or even a secondary HFS+ volume) so you can use it in the next step.

Install rEFInd

For all macOS versions starting with El Capitan (10.11) Apple has enabled System Integrity Protection (SIP). This security feature of macOS prevents changes to various areas of the Operating System including System-owned files. That means that you cannot install rEFInd directly on drives where SIP is enabled. In order to install rEFInd you will have to boot into Recovery. Make sure the rEFInd files are available on a drive that macOS can see and use, then follow these instructions:

1. Reboot the computer and hold down Command-R
2. Once in Recovery mode select Terminal from the Utilities menu
3. Find the volume where you have rEFInd stored (start with ls /Volumes)
4. Change into the rEFInd directory and run ./refind-install
5. You will still get a warning that SIP is enabled, but you can ignore it (SIP is enabled on the boot volume, but you're not installing it there

Full installation instructions can be found on the rEFInd site.

You may also want to theme rEFInd to look more 'mac-like'. I used the OSX Standard Theme 1.0 found here. Upate 20200906: This theme's installation instructions ask you to 'replace the EFI folder' in the rEFInd install you just did, it ALSO replaces the more curent version of rEFInd and the cryptographic keys that were provided. You probably shouldn't do that, though your milage may vary on getting this to work. At the time of this article's original publication, they were both the same version, but now, 3 years later, the theme's version of rEFInd is woefully outdated. Use with caution or update the components in the theme with the newer versions. (thank you Phillip!)

Test that rEFInd is installed and operational. Just reboot and you should be taken to the rEFInd boot menu, from there you should be able to boot into either macOS or Windows 10.

Note: rEFInd will automatically find what it believes to be bootable volumes. They probably all won't be bootable, through trial-and-error you should be able to find the correct macOS and Windows 10 volumes. You can then configure rEFInd to ignore some volumes, but save that for after you have everything working properly.

Install Linux##

Boot into macOS and have a USB key available to be reformatted, it can be pretty small (small works better), an 8GB drive is perfect.

In order to create a bootable USB drive, you can use the Terminal:

1. Run the Terminal from the Utilities folder under Applications
2. Change the directory to where you downloaded the ISO for your Linux installation, e.g. kali-linux-2016.1-amd64.iso
3. Find your USB key by running: diskutil list, note the drive name, e.g. disk2
4. Run the command: dd -if=kali-linux-2016.1-amd64.iso -of=/dev/disk2 bs=1m
5. The above command will take a long time to run, as it is imaging the ISO onto the USB drive. Once it finishes you should have a bootable USB key for Kali Linux (or whatever)

Alternatively, if you want a graphical imaging process, you can use UNetbootin as documented here for Ubuntu (just use Kali or whatever image you want).

You're now ready to install Linux. The reason you had to install rEFInd before installing Linux was that, in my experience, I could not get the standard macOS boot manager to recognize the USB drive I had prepared with Kali Linux. However, if you reboot now, you'll see the rEFInd boot menu. You can then insert your USB drive, then hit ESC to refresh the volumes and you should see the Linux installation drive appear. Select it for booting.

Follow the instructions for installing Linux, making sure to select the correct partition that you created while you were under Windows 10 earlier.

Completed

You should now have a triple-booting MacBook Pro. Using rEFInd you can select the appropriate OS and it should boot cleanly on your hardware.

In the event that rEFInd gets clobbered (you'll know, because a power-cycle takes you to the built-in macOS boot manager) you should still be able to boot into Windows, but you'll probably lose the ability to boot into Linux. Just follow the instructions and re-install rEFInd again and it should come back and allow you to boot again.

What you need to install Windows 10 on Mac

Brigadier 0.2.3 (March 7, 2016) set msiexec '/qb-' flag instead of '/qr' to avoid issues with modal dialog popups during Boot Camp MSI installation update default sucatalog to El Capitan. We would like to show you a description here but the site won’t allow us. Windows 10, 64-bit Windows 7 SP1, 64-bit. OS X El Capitan (10.11) eDrawings 2017. Apple Mac ® based machines running Windows using Boot Camp are not supported. For more information about using Windows on your Mac, open Boot Camp Assistant and click the Open Boot Camp Help button. If you're using an iMac (Retina 5K, 27-inch, Late 2014) or iMac (27-inch, Late 2013) or iMac (27-inch, Late 2012) with a 3TB hard drive and macOS Mojave or later, learn about an alert you might see during installation.

• MacBook introduced in 2015 or later
• MacBook Air introduced in 2012 or later
• MacBook Pro introduced in 2012 or later
• Mac mini introduced in 2012 or later
  

El Capitan Boot Camp Windows 10 Safe Mode

• iMac introduced in 2012 or later¹
• iMac Pro (all models)
• Mac Pro introduced in 2013 or later
  

The latest macOS updates, which can include updates to Boot Camp Assistant. You will use Boot Camp Assistant to install Windows 10.

64GB or more free storage space on your Mac startup disk:

• Your Mac can have as little as 64GB of free storage space, but at least 128GB of free storage space provides the best experience. Automatic Windows updates require that much space or more.
• If you have an iMac Pro or Mac Pro with 128GB of memory (RAM) or more, your startup disk needs at least as much free storage space as your Mac has memory.²

An external USB flash drive with a storage capacity of 16GB or more, unless you're using a Mac that doesn't need a flash drive to install Windows.

A 64-bit version of Windows 10 Home or Windows 10 Pro on a disk image (ISO) or other installation media. If installing Windows on your Mac for the first time, this must be a full version of Windows, not an upgrade.

• If your copy of Windows came on a USB flash drive, or you have a Windows product key and no installation disc, download a Windows 10 disk image from Microsoft.
• If your copy of Windows came on a DVD, you might need to create a disk image of that DVD.
  

How to install Windows 10 on Mac

To install Windows, use Boot Camp Assistant, which is included with your Mac.

1. Check your Secure Boot setting

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Learn how to check your Secure Boot setting. The default Secure Boot setting is Full Security. If you changed it to No Security, change it back to Full Security before installing Windows. After installing Windows, you can use any Secure Boot setting without affecting your ability to start up from Windows.

2. Use Boot Camp Assistant to create a Windows partition

Open Boot Camp Assistant, which is in the Utilities folder of your Applications folder. Follow the on-screen instructions.

• If you're asked to insert a USB drive, plug your USB flash drive into your Mac. Boot Camp Assistant will use it to create a bootable USB drive for Windows installation.
• When Boot Camp Assistant asks you to set the size of the Windows partition, remember the minimum storage-space requirements in the previous section. Set a partition size that meets your needs, because you can't change its size later.

3. Format the Windows (BOOTCAMP) partition

When Boot Camp Assistant finishes, your Mac restarts to the Windows installer. If the installer asks where to install Windows, select the BOOTCAMP partition and click Format. In most cases, the installer selects and formats the BOOTCAMP partition automatically.

4. Install Windows

Unplug any external devices that aren't necessary during installation. Then click Next and follow the onscreen instructions to begin installing Windows.

5. Use the Boot Camp installer in Windows

After Windows installation completes, your Mac starts up in Windows and opens a ”Welcome to the Boot Camp installer” window. Follow the onscreen instructions to install Boot Camp and Windows support software (drivers). You will be asked to restart when done.

• If the Boot Camp installer never opens, open the Boot Camp installer manually and use it to complete Boot Camp installation.
• If you have an external display connected to a Thunderbolt 3 port on your Mac, the display will be blank (black, grey or blue) for up to 2 minutes during installation.

How to switch between Windows and macOS

Restart, then press and hold the Option (or Alt) ⌥ key during startup to switch between Windows and macOS.

Learn more

If you have one of these Intel-based Mac models using OS X El Capitan or later, you don't need a USB flash drive to install Windows:

• MacBook introduced in 2015 or later
• MacBook Air introduced in 2017 or later³
• MacBook Pro introduced in 2015 or later³

El Capitan Boot Camp Windows 10

• iMac introduced in 2015 or later
• iMac Pro (all models)
• Mac Pro introduced in late 2013 or later
  

El Capitan Windows 10 Bootcamp Full

To remove Windows from your Mac, use Boot Camp Assistant, not any other utility.

El Capitan Boot Camp Windows 10 64

For more information about using Windows on your Mac, open Boot Camp Assistant and click the Open Boot Camp Help button.

El Capitan Boot Camp Windows 10 Iso

1. If you're using an iMac (Retina 5K, 27-inch, Late 2014) or iMac (27-inch, Late 2013) or iMac (27-inch, Late 2012) with a 3TB hard drive and macOS Mojave or later, learn about an alert you might see during installation.

2. For example, if your Mac has 128GB of memory, its startup disk must have at least 128GB of storage space available for Windows. To see how much memory your Mac has, choose Apple menu  > About This Mac. To see how much storage space is available, click the Storage tab in the same window.

3. These Mac models were offered with 128GB hard drives as an option. Apple recommends 256GB or larger hard drives so that you can create a Boot Camp partition of at least 128GB.

El Capitan Windows 10 Bootcamp Installer