Fixing "Setup was Unable to Create a New System Partition" Error While Installing Windows 7 via Bootcamp

Kelly Heffner Wilkerson, Co-Founder of Decipher Media
Kelly Heffner Wilkerson

Categories: macOS | View Comments

This is a little bit outside the scope of this blog, but I can't help myself. I recently got a new iMac, and tried to install Windows 7 on it using Bootcamp -- this is usually a painless process, but with the removal of DVD drives on the iMac and USB 3, it's a world of hurt. Here's my rundown of what worked seamlessly for me, after repeated bouts of getting stuck at the error "Setup was Unable to Create a New System Partition" during the Windows 7 install1.

  • If you have any half-completed installs, use the Bootcamp Assistant to remove the broken windows partition (in Bootcamp packaged with Mavericks, that should be checking the last checkbox only, to "remove").

  • Forget about installing form a USB thumb drive, and use an external DVD drive with a Windows 7 install disk2. (Use the Disk Utility to burn the ISO to the DVD if needed. You can download the ISO file for Windows 7 Ultimate, which will allow you to install Home, Ultimate, etc flavors of 64-bit Windows 7, here.)

  • Plug in your USB thumb drive, which we will still use to hold the Apple support files.

  • The ordering of things plugged into the USB ports seems to matter. On my iMac, there are four usb ports at the back; facing the back of the iMac from right to left I had: external DVD drive, thumb drive, blank, apple keyboard w/ non-apple mouse plugged into keyboard.

  • Use Bootcamp Assistant:

    • Uncheck the option to copy the installation files to a USB thumb drive. We don't need to copy the iso to the thumb drive, since we're using DVD.

    • Check the option to copy the support files to the thumb drive. We need these for Apple hardware drivers.

    • Check the option to install windows. We desperately want to do that!

  • If you've been trying to install from a USB thumb drive, you'll probably get a message about making the thumb not bootable. That is correct: we want to make the USB thumb drive not bootable now, as we are booting from the DVD and just using the thumb for support files.

  • Now the installation should work. Select the bootcamp partition, choose advanced, choose to format the BOOTCAMP partition as usual. Remember which partition said BOOTCAMP before you partition :)

  • Dance around your office (optional, but recommended!)

I believe the root of this issue is a unhappy melding of USB 3.0 issues and having a bootable USB thumb drive be the source of installation.

Edit: Since the writing of this article, readers have sent me feedback that using USB 2.0 thumb drive works. That is great news (especially since a USB DVD drive isn't always lying around anymore) and I appreciate the feedback from people sharing their experiences!

  1. I've also summarized in the Apple forums here! https://discussions.apple.com/thread/6467918 

  2. The external DVD drive I used was an Apple USB SuperDrive. I borrowed it from a friend!