Updating boot support partitions for the volume
If that’s the case, all you need to do is reinstall Mac OS (or Mac OS) as usual and it should be fixed in the process: Assuming you choose to simply reinstall Mac OS X and you don’t attempt to format the drive or do anything else, then only the Mac OS system software will be replaced and the EFI partition will be recreated in the process.
In other words, no personal data, files, or apps should be lost in the process if all you are choosing to do is reinstall Mac OS X.
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At this point, you can go ahead and partition the drive as usual, this time without any such “Partition Failed” error message appearing in Disk Utility.
Often users may see this error when attempting to partition a Mac boot drive for dual booting or for some similar purpose.
But, fortunately fsck does work just fine for most situations where ‘partition failed’ error is showing up in Mac OS, so give it a try.
Do note that “fsck” can take a while to run and complete, depending on the size of the drive.
After wrangling with a broken EFI partition on a Mac recently, I personally found the fastest and most foolproof method of fixing the EFI partition and to get the Mac to boot again was .
The EFI problem is then confirmed by booting into Recovery mode and running Disk Utility, often from an another drive.
Since a broken EFI partition may prevent a Mac from starting up properly it can be a challenge to repair.
If you suspect that may be the case, you may want to attempt to repair the drive through Disk Utility and run Apple Hardware Test on the Mac to see if any hardware related disk errors appear.
If the drive is failing, you will need to replace it, and you’d want to do that sooner than later to avoid data loss.