I needed to resize my Boot Camp partition so I used Gparted to move and resize it. This seemed to work, except that now I can't boot into Windows.

I can boot into OS X just fine. OS X can recognize the Boot Camp partition and view its contents. When I try to reboot into Windows, however I get the message:

No bootable device -- insert boot disk and press any key

The only solutions I've been able to find online suggest that the only way to fix this is to either clone the drive or remove the Windows partition and re-install it.

Is there any way to fix my Windows partition so that I don't have to reinstall Windows again?


3 Answers 3


It might be that your Windows partition is just fine, but it's your Protective Master Boot Record that's screwed up. Macs use the more modern GUID Partition Table (GPT) format to define where each of the partitions are, but for Boot Camp booting into Windows, you need a fake version of a traditional Master Boot Record (MBR) on the drive.

Apple's Boot Camp Assistant takes care of creating this "Protective Master Boot Record" or "PMBR" as they call it. Apple's tools are aware of the need for keeping the GPT and PMBR in sync, but perhaps GParted wasn't so careful.

There are third-party tools such as rEFIt that, among other things, can probably help you get your GPT and your PMBR back in agreement after some other tool has messed them up.

Or you might try using Mac OS X v10.7.x (Lion)'s Disk Utility to repair the drive. Make sure you select the whole disk, not a partition.

Another fix might be to use Disk Utility to slightly resize a partition, so that it has to rewrite the GPT and PMBR.

  • Both you and Eli had the correct solution. rEFIt was able to sync my GPT and PMBR, which made Windows bootable again. I've accepted your answer because it helped me understand the issue in more detail so I know what went wrong. Jan 4, 2012 at 4:06

I had the same problem. Refit did not work for me, however I did the following steps and one of them seemed to fix it. Sorry I can't be more specific on which step it was

  1. Boot from the OSX lion DVD
  2. Repair the top level disk
  3. Resize the OSX parition slightly then resize back
  4. Boot into the windows 7 DVD and repair the boot loader problems, by going to "Repair your computer", selecting your Windows and "Startup Repair".
  5. Boot back into OSX and set bootcamp at the startup disk from the system preferences...

Try installing rEFIt and using it to sync the GPT tables. Don't know if that will work, but it's worth a shot.

It could be that the Windows bootloader is messed up. I'd try booting from a Windows recovery CD/DVD and rebuilding the bootloader/MBR.

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