How to Fix a Broken EFI Partition

It may be the result of an unsuccessful attempt to install Windows via Boot Camp or of simply not paying attention during the installation process, but a Mac’s Extensible Firmware Interface partition can go belly up. While the reason for a broken EFI partition can vary, the symptoms don’t and neither does the way to fix it. Read on if you have a broken EFI partition to find out how to fix it.

Symptoms of a broken EFI partition

As you may already know, the EFI System Partition or ESP is a special partition on a Mac from which the initial system boot-time device drivers can be loaded and that was created as a BIOS replacement. This means that if there are issues with the EFI partition, then problems arise.

That means computer startup issues, so be prepared as this could be one of the reasons for your Mac refusing to boot. In some cases, the Mac won’t show any signs of trouble until you want to install a new version of macOS, and when that moment comes the attempt to upgrade will be unsuccessful with various errors to deal with.

How to address the broken EFI partition issue

First things first, use Disk Utility to verify and repair the drive. To do that, simply select the internal drive listed in the utility and run First Aid. By doing so you’ll let Apple’s built-in disk management utility fix the problem. If the exit code is zero, then everything is back to normal and the issue is resolved. However, if the repair is unsuccessful, don’t attempt to erase the partition or the whole drive with Disk Utility, nor should you rename the broken EFI partition because you’ll likely run into further issues.

To fix the problematic EFI partition you have two options, either reinstall macOS or use Terminal to run a series of commands.

Reinstall macOS

While not too elegant or tricky, the easiest way to fix a broken EFI is simply to reinstall macOS. This is possible in two ways, either through macOS Recovery or – if the Mac won’t boot at all – macOS Internet Recovery. It goes without saying that you should back up your Mac (if you can) before the process.

To reinstall macOS with Recovery mode, you’ll only need to follow these steps:

The macOS reinstall via Internet Recovery is useful if your Mac doesn’t boot at all, you just need a fast and reliable internet connection.

Perform terminal commands (only on HFS+ formatted drives)

This is more complicated and requires more technical confidence, as well as knowledge of the macOS system. The very first step in getting the EFI partition back is to check the volumes that macOS is able to see by running this command in Terminal:

diskutil list

Also, check whether there are any encrypted disks by running the following command:

diskutil cs list

As you can see from the screenshot below, the EFI partition file system is correctly classified as EFI type; errors occur when this EFI partition – for whatever reason – receives a new file system and is classified as something else, as was the case when a user reported to the Apple community that their EFI partition was incorrectly classified as HFS+.

With the details of the available volumes and encrypted disks to hand, proceed with the following steps:

1. 1. Download GPT Fdisk.
   2. Disable SIP.
   3. Boot normally, and run the following command:

sudo gdisk /dev/disk0

From here you’ll enter gdisk interactive mode, where commands are single characters followed by return. Run commands in the following order:

1. 1. t (to change the partition type)
   2. 1 (for GUID Partition Table 1)
   3. EF00 (to EFI partition)
   4. p (to print/display)
   5. w (to write)
   6. y (to confirm write).

After this process, reboot the system and then enter the following command:

diskutil repairDisk disk0

Unfortunately, the gdisk command is no longer available on macOS High Sierra, so this trick only works on systems prior to APFS. Have you managed to fix the broken EFI partition using another method? If so, share it with us in the comments section.