Mac – Migrate Bootcamp partition to a new Mac

I encountered this error a few months ago when I attempted to create a partition. I followed bootcamp's instructions (ie used time machine to backup the entire disk and reformat) and all worked fine.

Took a while to perform the backup and restore though :(

DO NOT use gptsync (the program whose output you posted) on your disk -- at least not yet!

The critical question is: How did you create your exFAT partition? If you created it using OS X's Disk Utility, you may be able to get it working again by using gptsync.

If you created the partition from Windows, STOP!! Modifying partitions on a dual-boot Windows/OS X system from Windows, using the standard Windows tools, will modify your disk's hybrid MBR without modifying your real partition definitions in the GUID Partition Table (GPT). If you subsequently use gptsync on the disk, the GPT definitions will overwrite the (Windows-modified) hybrid MBR partitions, thus making it impossible for Windows to access whatever partition(s) you modified. If you get this far, this situation can be very difficult to fix. If you've done this, your best hope is to write down on paper the start and end points, expressed in sectors, of every partition on the disk, using both the MBR and the GPT values. You can then sort it through, figure out which ones are accurate, create a new GPT with all the correct values, and then re-create a new hybrid MBR with gptsync or gdisk. This is obviously rather involved and requires a lot of understanding to do successfully, so if you've used Windows to create your new partition, be prepared to spend some time reading up and learning before you do anything. Begin with the links in this paragraph.

In either case, just to be sure, I recommend you use gdisk to verify your disk. Launch it on the disk and type v. It will produce a report of any inconsistencies, including any mis-matched hybrid MBR and GPT partitions it finds.

Edit: Oops; I missed your edit on the first read. If you've already run gptsync, then gdisk's verification will probably be useless. The rest of what I wrote still applies, but if you used Windows to create your exFAT partition, the simplest solution is to re-install Windows. You'll lose all your user files, of course. If you've got important user files, you could try using TestDisk to try to recover the lost partition or PhotoRec to try to recover individual files. Please post back with clarification about how you created that new partition for more individualized advice.