First Aid on Physical Disk Fails ?!!

Question

Level 1

12 points

First Aid on Physical Disk Fails ?!!

I'm somewhat at my wits end having spent the last month with some sort of First Aid issue on my work 27" iMac Intel 2020....

It was saying that the data volume First Aid would just fail. So I thought the data was corrupt and bought a new Studio to replace it thinking I could then Erase everything on this iMac and install fresh OS in Recovery and repurpose this for my personal use.

All seemed okay, migrated my old personal Time Machine over to this newly Erased iMac, and things seemed to be fine.... Until my 4th Super Duper backup failed.

So I ran Recovery First Aid, and this time while the Data, Volumes and Container are all fine - now it says First Aid on the very top Physical Disk "Apple SSD AP2048N Media" failed - repeatedly.

It says "Problems were found with the partition map which might prevent booting. Couldn't mount disk: (-69842)

Does this mean basically that the Hard drive in the iMac is toast? It would be a shame as I love this big Nano screen 27" iMac and its only 5 years old... sob

Any ideas?

Thanks!

iMac 27″, macOS 15.5

Posted on Jun 7, 2025 4:16 PM

Reply

Answer 1

John Galt

Level 10

151,848 points

Jun 7, 2025 4:39 PM in response to lilskye2

Refer to Repair a storage device in Disk Utility on Mac - Apple Support.

Ignore Step 1 because you will be performing that "repair" on the boot device. Begin with the Note in Step 2.

Then, follow each one of the remaining steps in the provided order.

If you already did all that, then proceed below the horizontal rule.

That's all you can do.

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Answer 2

John Galt

Level 10

151,848 points

Jun 7, 2025 6:47 PM in response to lilskye2

I will say that this will be my third Erase all Contents and reinstall of Mac OS (not sure if this actually "reformats" the disk or if that is something I have to purposely do somehow? I presume that is what DU does? Yes?

To be clear, if you arrived at this step in Repair a storage device in Disk Utility on Mac:

If Disk Utility can’t repair your disk, or you receive a report that the First Aid process failed, try to repair the disk or partition again. If that doesn’t work, back up as much of your data as possible, reformat the disk, ...

... what that's telling you to do is to Erase and reformat a storage device in Disk Utility on Mac.

Specifically, follow the instructions described in "If you want to erase your startup disk."

But that may be getting ahead of ourselves. Start at the very beginning. Was there a reason you ran Disk Utility to begin with?

In other words, what was it that led to your original concern?

The reason for asking is that if DU reported "Problems were found with the partition map which might prevent booting" yet the Mac apparently boots and runs ok, then I recommend you do absolutely nothing — other than maintaining Time Machine backups of course. Please clarify that before taking any more action. I'll explain later.

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Answer 3

lilskye2 Author

Level 1

12 points

Jun 7, 2025 5:52 PM in response to John Galt

Thanks for your quick reply.

Yes I have already done all these steps a few times and at least my data is backed up on Time Machine (and I still have the original personal 2018 iMac that I was replacing with this one. So all is not lost.

I will say that this will be my third Erase all Contents and reinstall of Mac OS (not sure if this actually "reformats" the disk or if that is something I have to purposely do somehow? I presume that is what DU does? Yes?

It is sounding more to me like this disk is dying or corrupted/damaged in some way. And if I understand correctly there's no way for me to use the iMac by instead booting from an external drive as it is a T2 (though I see people claim I can change some security setting in Recovery to allow this???)

I'm willing to try anything to save the 27" iMac and wish they still made these!!!!!!!!!

I will await your comments to this before I attempt to again reinstall the OS.

Thanks!