Fixing a Broken EFI Partition on Mac
Though it is an unusual occurrence, a Mac may encounter a broken or damaged EFI partition which typically prevents the Mac from booting and the Mac OS system software from loading. This is usually demonstrated as a boot screen that is stuck on the Apple logo, sometimes with or without a wait cursor that spins endlessly. 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. There are options to attempt to manually rebuild, create, or repair the EFI partition, typically with fsck, diskutil, and third party tools like got frisk. 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 simply reinstalling Mac OS X onto the computer. I fiddled with the other options, but ultimately just reinstalling Mac OS system software did the job for the situation I encountered.
It is not the most elegant solution, but reinstalling Mac OS system software should repair a broken or damaged EFI partition, or if one is missing somehow it will recreate one in the OS install process. You can reinstall Mac OS X using any of three methods: using a bootable disk, using Internet Recovery, or using normal Recover mode, which approach you will probably depend on
Hopefully you have made a full backup of the Mac before the EFI partition failed to begin with, otherwise you should complete a backup before attempting to reinstall MacOS system software.
How to Fix Broken EFI Partitions with a System Software Reinstall
When booted from a recovery volume, you should run Disk Utility beforehand to verify and attempt to repair the drive in question – though there is a good chance you have already tried that and that is when you discovered the EFI problem to begin with. If that’s the case, all you need to do is reinstall Mac OS (or MacOS) as usual and it should be fixed in the process:
- If the Mac won’t boot at all – reinstall Mac OS X with Internet Recovery, this requires a stable and reasonably fast high speed internet connection, or you can use a USB boot disk if you have one available
- If the Mac Recovery partition works to boot, but not the primary OS – reinstall Mac OS X with regular Recovery mode
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. If you go a route aside from simply reinstalling Mac OS X, you may lose data.
Finally, something else to keep in mind is that sometimes damaged or broken EFI partitions can be an indicator of an impending disk failure, or some other problem with the hard drive. 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.
Know of another method of fixing broken EFI partitions? Have any related tips or thoughts that are helpful? Let us know in the comments!