Windows 7: Setup was unable to create a system partition or locate an existing partition.

Over the past week, I’ve installed Windows 7 and OS X more times than I can count. In attempting to figure out the easiest way to dual boot Windows 7 and OS X, I’ve also partitioned my drive a good 30+ times. So.. after messing up with an EFI bootloader, I was suddenly unable to re-install Windows 7. I encountered the error: Setup was unable to create a system partition or locate an existing partition. I also ran into the error: Windows cannot be installed on disk 0 partition 1.

I used Gparted to repartition my drive, and even used Disk Utility but repeatedly encountered the above errors.

As it turns out, I had another System disk attached (OS X on a USB drive) to my laptop and once I unplugged it, I was able to successfully install Windows 7.

Chrissy is a Cloud and Datacenter Management & Data Platform MVP who has worked in IT for over 20 years. She is the creator of the popular SQL PowerShell module dbatools, holds a master's degree in Systems Engineering and is coauthor of Learn dbatools in a Month of Lunches. Chrissy is certified in SQL Server, Linux, SharePoint and network security. You can follow her on Twitter at @cl.

Posted in Windows
3 comments on “Windows 7: Setup was unable to create a system partition or locate an existing partition.
  1. Nice! Only a real nerd would have OS X mounted on a USB drive! Only a classy nerd would admit this partitioning blunder on the Internet!

  2. Eric J says:

    Yeah, same thing happening to me right now. Except the usb drive is for my raid drivers. The same thing happened when I was installing vista, but I just can't remember for the life of me how I fixed it. I just know it was something extremely simple that I overlooked time again.

  3. tankman says:

    I can shed some light on the "Windows cannot be installed on disk 0 partition 1." I came across this on 4 different drives, the first 2 had Gparted run on them just a few minutes before. I thought this was the problem but it isn't.

    Here is what I found. Even though you can swap drives (SATA) during the install process, you can not use the new drive unless it was there during the system post during boot as the BIOS has to see the drive for some reason (I never had this problem in Linux).

    So, the next time you have this error, turn the machine off, make sure the target HD is plugged in and start it up. If the BIOS doesn't see the drive you will get this error.

    I was about to give up on this as it just didn't make sense. Very frustrating!

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