problem with the EFI system partition’s file system

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Level 1

4 points

problem with the EFI system partition’s file system

New, unused 4TB external hard drive from OWC, GUID Partition Map, HFS+. Need to be bootable. First to clone iMac - High Sierra (HFS+) prior to upgrade for Ventura. Then to clone iMac’s Ventura and MacBook Pro’s Big Sur.

For routine check. From User Account, Disk Utility First Aid failed: “The partition map needs to be repaired because there’s a problem with the EFI system partition’s file system. : (-69766). Operation failed… Ran First Aid from Recovery, same result.

MacBook Pro 13″, macOS 11.7

Posted on Oct 4, 2025 5:59 PM

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Answer 1

Top-ranking reply

HWTech

Level 9

68,198 points

Oct 4, 2025 6:41 PM in response to alinnova

Try running First Aid on the physical drive. You may need to click "View" within Disk Utility before the physical drives and hidden Containers appear on the left pane of Disk Utility. If First Aid is unable to repair things, then you will need to erase the whole physical drive.

FYI, It is best to erase the whole physical drive. The partition & formatting on a drive from the factory can sometimes be problematic. I will erase the whole physical drive every time just so that it will have a fresh new partition table.

Erase and reformat a storage device in Disk Utility on Mac - Apple Support

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Answer 2

Oct 5, 2025 4:47 PM in response to HWTech

HWTech wrote:

FYI, It is best to erase the whole physical drive. The partition & formatting on a drive from the factory can sometimes be problematic. I will erase the whole physical drive every time just so that it will have a fresh new partition table.

EFI had some “fun” bugs within itself here, too. Absolutely: erase before use.

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Answer 3

alinnova Author

Level 1

4 points

Oct 5, 2025 1:14 PM in response to HWTech

Many thanks. Worked like a charm. I had already run First Aid on the Physical Drive before writing, so I went directly to the Erase function. Now see beautiful new partition unencumbered with the vendor’s fluff.

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Answer 4

HWTech

Level 9

68,198 points

Oct 5, 2025 4:34 PM in response to alinnova

Thanks for the update. I'm glad that worked.

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