Fix 'Problems were found with the partition map' in Disk Utility

"Problems were found with the partition map which might prevent booting" is a Mac error that happens when checking an internal or external hard drive using the First Aid feature in Disk Utility or running commands in Terminal. Some may receive extra information about the partition map problems, such as:

It's important that you back up your data before carrying on with the solutions if you still can access the drive. You can recover the lost data following the next section if the drive is inaccessible.

How to recover data when seeing 'Problems were found with the partition map'?

When experiencing "Problems were found with the partition map" on Mac's startup disk, your Mac may have issues booting up, such as:

If the error occurs on your external hard drive, you likely find the external hard drive grayed out in Disk Utility and isn't accessible from your desktop or Finder.

Often, the most effective way to fix the "Problems were found with the partition map" error, regardless of whether it happens on the internal or external hard drive, is to reformat the disk, which will erase all your data. So, the utmost important thing now is to recover your lost data from the inaccessible drive.

To retrieve data from an inaccessible or unbootable internal or external hard drive, you should employ the professional data recovery tool: iBoysoft Data Recovery for Mac. It's designed with usability and capability in mind, able to restore over 1000 file formats, including photos, videos, documents, audio files, emails, archives, etc., from an unbootable Mac and inaccessible, unmountable, or corrupted external hard drives, USB flash drives, SD cards, and other common storage devices.

It's compatible with Intel, T2, and Apple Silicon Macs running on Mac OS X 10.11 ~ macOS 13 Ventura. iBoysoft Data Recovery also allows you to free preview files before recovery.

Here's how to install it on your Mac:

If you're receiving "Problems were found with the partition map" on an unbootable Mac:

How to fix 'Problems were found with the partition map' on internal hard drives?

After securing the essential files on your Mac, you can follow the solutions below to fix "Problems were found with the partition map which might prevent booting" on Mac.

• Solution 1: Repair partition map in macOS Recovery Mode
• Solution 2: Fix the drive using fsck in Single User Mode
• Solution 3: Reformat the startup disk in Internet Recovery

Solution 1: Repair partition map in macOS Recovery Mode

If "Problems were found with the partition map" resides in the details of the error reading, "First Aid found corruption that needs to be repaired. To repair the startup volume, run First Aid from Recovery. Click Done to continue." Our advice is to follow the instruction and run First Aid from macOS Recovery.

Wait for the scan to complete. If the issue persists, run First Aid for the volumes under the disk one by one and check if they have issues. If Disk Utility reports no error on the internal volumes and your Mac boots up fine, you shouldn't worry too much about it.

Solution 2: Fix the drive using fsck in Single User Mode

Suppose the repair in Disk Utility failed with errors like "Partition map check failed because no slices were found." In this case, you can run fsck in Single User Mode to fix the drive. Fsck, which is shortened for "File System Consistency Check," is a command-line tool that verifies and repairs the underlying structure of a hard drive.

Solution 3: Reformat the startup disk in Internet Recovery

If fsck can't repair the partition map, you can write a new one by reformatting the drive. It's worth mentioning that you should erase the whole disk (such as Apple SSD) rather than its volumes like Macintosh HD, as erasing the volume won't touch the partition map.

Before you erase macOS, make sure you have backed up your files with Time Machine or recovered lost data from the Mac that won't turn on, as guided in the first section of this post.

Erasing the startup disk should have fixed the partition map problems. Now, you need to reinstall macOS to use your Mac. To do it, simply exit Disk Utility and choose "Reinstall macOS" to get the latest version of the previously installed macOS. 

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How to fix 'Problems were found with the partition map' on external hard drives?

The partition map can become corrupt or damaged from an error in writing to the drive when creating or deleting partitions or from a media error where a bit of data on that particular sector or block has become corrupt. It might also occur if the external hard drive was not ejected properly.

Here are the solutions to try if Disk Utility reports "Problems were found with the partition map" on external hard drives.

Solution 1: Manually mount the drive

If the external hard drive is grayed out in Disk Utility, you can manually mount it by clicking the Mount button in the menu bar. This should also show the drive on your desktop if done successfully.

Solution 2: Reformat the external drive

If the drive can't be mounted, the best solution is to reformat it with a clean, new file system. Erasing the disk in the drive level reformats the area where the partition map and the directory are written, wiping the damaged or faulty partition map. Since reformatting a drive will delete its data, you should ensure your data is copied to another storage device before starting.

Haven't you recovered data from the external hard drive yet? Free download iBoysoft Data Recovery for Mac here!

Then follow the steps below to repair the partition map:

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